A National Guard soldier stands near the scene of a twin bombing at the Boston Marathon, on April 16, 2013 in Boston, Massachusetts. (Photo by Spencer Platt/Getty Images)
Boston Deals With Aftermath Of Marathon Explosions
A man walks by portable toilets near the scene of a twin bombing at the Boston Marathon, on April 16, 2013 in Boston, Massachusetts. (Photo by Spencer Platt/Getty Images)
Boston Deals With Aftermath Of Marathon Explosions
Debris and litter cover an empty street near the scene of a twin bombing at the Boston Marathon, on April 16, 2013 in Boston, Massachusetts.(Photo by Spencer Platt/Getty Images)
Boston Deals With Aftermath Of Marathon Explosions
A Boston police officer stands near the scene of a twin bombing at the Boston Marathon, on April 16, 2013 in Boston, Massachusetts. (Photo by Spencer Platt/Getty Images)
Boston Deals With Aftermath Of Marathon Explosions
Unclaimed finish line bags are left near the scene of a twin bombing at the Boston Marathon, on April 16, 2013 in Boston, Massachusetts. (Photo by Spencer Platt/Getty Images)
Boston Deals With Aftermath Of Marathon Explosions
Unclaimed finish line bags are viewed near the scene of a twin bombing at the Boston Marathon, on April 16, 2013 in Boston, Massachusetts. (Photo by Spencer Platt/Getty Images)
Boston Deals With Aftermath Of Marathon Explosions
Boston Police stand near the scene of a twin bombing at the Boston Marathon, on April 16, 2013 in Boston, Massachusetts. (Photo by Spencer Platt/Getty Images)
Boston Deals With Aftermath Of Marathon Explosions
Unclaimed food sits near the scene of a twin bombing at the Boston Marathon, on April 16, 2013 in Boston, Massachusetts. (Photo by Spencer Platt/Getty Images)
Boston Deals With Aftermath Of Marathon Explosions
A Boston police officer stands near the scene of a twin bombing at the Boston Marathon, on April 16, 2013 in Boston, Massachusetts. (Photo by Spencer Platt/Getty Images)
Boston Deals With Aftermath Of Marathon Explosions
A Boston police officer stands near the scene of a twin bombing at the Boston Marathon, on April 16, 2013 in Boston, Massachusetts. (Photo by Spencer Platt/Getty Images)
Boston Deals With Aftermath Of Marathon Explosions
National Guard soldiers stand near the scene of a twin bombing at the Boston Marathon, on April 16, 2013 in Boston, Massachusetts. (Photo by Spencer Platt/Getty Images)
Boston Deals With Aftermath Of Marathon Explosions
A piece of debris rests against a police barricade near the scene of a twin bombing at the Boston Marathon, on April 16, 2013 in Boston, Massachusetts. (Photo by Spencer Platt/Getty Images)
Boston Deals With Aftermath Of Marathon Explosions
The marathon finish line bridge is seen on Boylston Street on April 16, 2013 in Boston, Massachusetts. (Photo by Darren McCollester/Getty Images)
Boston Deals With Aftermath Of Marathon Explosions
Swat team members and special police units assemble in the Boston Common on April 16, 2013 in Boston, Massachusetts. (Photo by Darren McCollester/Getty Images)
Boston Deals With Aftermath Of Marathon Explosions
Police units assemble along the Boston Public Garden on April 16, 2013 in Boston, Massachusetts. (Photo by Darren McCollester/Getty Images)
Boston Deals With Aftermath Of Marathon Explosions
Swat team members and special police units assemble in the Boston Common on April 16, 2013 in Boston, Massachusetts. (Photo by Darren McCollester/Getty Images)
Boston Deals With Aftermath Of Marathon Explosions
Swat team members and special police units assemble in the Boston Common on April 16, 2013 in Boston, Massachusetts. (Photo by Darren McCollester/Getty Images)
Boston Deals With Aftermath Of Marathon Explosions
A police officer stands guard at the corner of Boylston and Arlington Streets with the marathon finish line bridge in the distance on April 16, 2013 in Boston, Massachusetts. (Photo by Darren McCollester/Getty Images)
Boston Deals With Aftermath Of Marathon Explosions
An MP with the 747 checks an ID on Massachusetts Avenue on April 16, 2013 in Boston, Massachusetts. (Photo by Darren McCollester/Getty Images)
Boston Deals With Aftermath Of Marathon Explosions
An MP with the 747 checks an ID on Massachusetts Avenue on April 16, 2013 in Boston, Massachusetts. (Photo by Darren McCollester/Getty Images)
Boston Deals With Aftermath Of Marathon Explosions
A SWAT team vehicle stands guard on Dalton Street near Boylston Street on April 16, 2013 in Boston, Massachusetts. (Photo by Darren McCollester/Getty Images)
Boston Deals With Aftermath Of Marathon Explosions
Boston police officers stand at barriers closing off Boylston Street April 16, 2013 in Boston, Massachusetts, in the aftermath of two explosions that struck near the finish line of the Boston Marathon April 15. (STAN HONDA/AFP/Getty Images)
Boston Deals With Aftermath Of Marathon Explosions
Charlie Johnston stands on Newbury Street and looks toward the finish line area a block away from Boylston Street April 16, 2013 in Boston, Massachusetts, in the aftermath of two explosions that struck near the finish line of the Boston Marathon April 15. (STAN HONDA/AFP/Getty Images)
Boston Deals With Aftermath Of Marathon Explosions
A crumpled runners' blanket on a sidewalk April 16, 2013 in Boston, Massachusetts, in the aftermath of two explosions that struck near the finish line of the Boston Marathon. (Photo: STAN HONDA/AFP/Getty Images)
Boston Deals With Aftermath Of Marathon Explosions
Boston police officers near a Humvee April 16, 2013 in Boston, Massachusetts, in the aftermath of two explosions that struck near the finish line of the Boston Marathon. (credit: STAN HONDA/AFP/Getty Images)
Boston Deals With Aftermath Of Marathon Explosions
Police officers stand near the Boston Marathon finish line from Clarendon and Boylston Street on April 16, 2013 in Boston, Massachusetts. (Photo by Darren McCollester/Getty Images)
Boston Deals With Aftermath Of Marathon Explosions
People walk along Clarendon Street and Boylston Street on April 16, 2013 in Boston, Massachusetts. (Photo by Darren McCollester/Getty Images)
Boston Deals With Aftermath Of Marathon Explosions
Newspapers are on sale at a stand on Newbury Street on April 16, 2013 in Boston, Massachusetts. (Photo by Darren McCollester/Getty Images)
Boston Deals With Aftermath Of Marathon Explosions
A sign on a door makes notice of being closed at Trident Booksellers Cafe on Newbury Street shows closed on April 16, 2013 in Boston, Massachusetts. (Photo by Darren McCollester/Getty Images)
Boston Deals With Aftermath Of Marathon Explosions
A runner stands at a security gate near the scene of a twin bombing at the Boston Marathon on April 16, 2013 in Boston, Massachusetts. (Photo by Spencer Platt/Getty Images)
Boston Deals With Aftermath Of Marathon Explosions
Claire Schaeffer Dufy walks with a sign she made to support her runner husband, Scott, near the scene of a twin bombing at the Boston Marathon on April 16, 2013 in Boston, Massachusetts. (Photo by Spencer Platt/Getty Images)
Boston Deals With Aftermath Of Marathon Explosions
People congregate at a security gate near the scene of a twin bombing at the Boston Marathon on April 16, 2013 in Boston, Massachusetts. (Photo by Spencer Platt/Getty Images)
Boston Deals With Aftermath Of Marathon Explosions
People walk to work near the scene of a twin bombing at the Boston Marathon on April 16, 2013 in Boston, Massachusetts. (Photo by Spencer Platt/Getty Images)
Boston Deals With Aftermath Of Marathon Explosions
A Boston police officer stands guard near the scene of a twin bombing at the Boston Marathon on April 16, 2013 in Boston, Massachusetts. (Photo by Spencer Platt/Getty Images)
Boston Deals With Aftermath Of Marathon Explosions
A Boston police officer stands near the scene of a twin bombing at the Boston Marathon on April 16, 2013 in Boston, Massachusetts. (Photo by Spencer Platt/Getty Images)
Boston Deals With Aftermath Of Marathon Explosions
The unfinished meals of fleeing customers are left on tables at an outdoor restaurant near the scene of a twin bombing at the Boston Marathon on April 16, 2013 in Boston, Massachusetts. (Photo by Spencer Platt/Getty Images)
Boston Deals With Aftermath Of Marathon Explosions
Unused thermal blankets for marathon participants are piled near the scene of a twin bombing at the Boston Marathon on April 16, 2013 in Boston, Massachusetts. (Photo by Spencer Platt/Getty Images)
Boston Deals With Aftermath Of Marathon Explosions
A Boston police officer stands near the scene of a twin bombing at the Boston Marathon on April 16, 2013 in Boston, Massachusetts. (Photo by Spencer Platt/Getty Images)
Boston Deals With Aftermath Of Marathon Explosions
A runner stands at a security gate near the scene of a twin bombing at the Boston Marathon on April 16, 2013 in Boston, Massachusetts. (Photo by Spencer Platt/Getty Images)
Boston Deals With Aftermath Of Marathon Explosions
A Boston police officer stands near the scene of a twin bombing at the Boston Marathon on April 16, 2013 in Boston, Massachusetts. (Photo by Spencer Platt/Getty Images)
Boston Deals With Aftermath Of Marathon Explosions
Unused thermal blankets for marathon participants are piled near the scene of a twin bombing at the Boston Marathon on April 16, 2013 in Boston, Massachusetts. (Photo by Spencer Platt/Getty Images)
Boston Deals With Aftermath Of Marathon Explosions
Closed streets are viewed blocks away from the scene of a twin bombing at the Boston Marathon on April 16, 2013 in Boston, Massachusetts. (Photo by Spencer Platt/Getty Images)
Boston Deals With Aftermath Of Marathon Explosions
National Guard soldiers guard a roadblock near the scene of a twin bombing at the Boston Marathon on April 16, 2013 in Boston, Massachusetts. (Photo by Spencer Platt/Getty Images)
Boston Deals With Aftermath Of Marathon Explosions
Boston Mayor Thomas Menino, who recently broke his leg, arrives at a press conference April 16, 2013 in Boston, Massachusetts, in the aftermath of two explosions that struck near the finish line of the Boston Marathon April 15. (STAN HONDA/AFP/Getty Images)
Boston Deals With Aftermath Of Marathon Explosions
BOSTON - APRIL 16: Boston Mayor Thomas Menino speaks at a press conference surrounded by State and Federal officials including (L to R) U.S. Senator Elizabeth Warren, FBI Special Agent in Charge Richard DesLauriers, U.S. Attorney Carmen Ortiz, Governor Deval Patrick, and U.S. Congressman Stephen Lynch April 16, 2013 at the Westin Copley in Boston, Massachusetts. (Photo by Darren McCollester/Getty Images)
Boston Deals With Aftermath Of Marathon Explosions
Marathoners wait with packed bags for a train at Back Bay Station April 16, 2013 in Boston, Massachusetts. (Photo by Darren McCollester/Getty Images)
Boston Deals With Aftermath Of Marathon Explosions
Flags fly at half staff near Trinity Church April 16, 2013 in Boston, Massachusetts, in the aftermath of two explosions that struck near the finish line of the Boston Marathon on Monday. (STAN HONDA/AFP/Getty Images)
Boston Deals With Aftermath Of Marathon Explosions
Nicholas Yanni of Boston, MA, prepares to speak at a press conference at Tufts Medical Center after being injured at yesterday's bomb attack on the Boston Marathon April 16, 2013 in Boston, Massachusetts. (Photo by Darren McCollester/Getty Images)
Boston Deals With Aftermath Of Marathon Explosions
Flowers are left at a security gate near the scene of the bombing attack at the Boston Marathon on April 16, 2013 in Boston, Massachusetts. (Photo by Spencer Platt/Getty Images)
Boston Deals With Aftermath Of Marathon Explosions
A woman prays at a security gate near the scene of yesterday's bombing attack at the Boston Marathon on April 16, 2013 in Boston, Massachusetts. (Photo by Spencer Platt/Getty Images)
Boston Deals With Aftermath Of Marathon Explosions
People congregate, including many runners, at a security gate near the scene of yesterday's bombing attack at the Boston Marathon on April 16, 2013 in Boston, Massachusetts. (Photo by Spencer Platt/Getty Images)
Boston Deals With Aftermath Of Marathon Explosions
A young runner (L) collects his thoughts in a church blocks away from the scene of yesterday's bombing attack at the Boston Marathon on April 16, 2013 in Boston, Massachusetts. (Photo by Spencer Platt/Getty Images)
Boston Deals With Aftermath Of Marathon Explosions
A Boston Police officer lifts the tape for a family to leave flowers in front of the home of the Richard family whose eight-year-old son, Martin, was killed by an explosion near the finish line of the Boston Marathon, on April 16, 2013 in Boston, Massachusetts. (Photo by Jared Wickerham/Getty Images)
Boston Deals With Aftermath Of Marathon Explosions
Boston Deals With Aftermath Of Marathon Explosions
Flowers and a message are left on Newbury Street April 16, 2013 in Boston, Massachusetts, a few blocks from where two explosions struck near the finish line of the Boston Marathon on Monday. Three people, including a child, were killed and more than 170 were injured in the explosions that occurred a few seconds apart near the finish line of the 117th rendition of the world's oldest international marathon. (credit: STAN HONDA/AFP/Getty Images)
Boston Deals With Aftermath Of Marathon Explosions
Boston Deals With Aftermath Of Marathon Explosions
Flowers and a message were left at Boylston and Arlington streets on April 16, 2013 in Boston, a few blocks from where two explosions struck near the finish line of the Boston Marathon on April 15. (STAN HONDA/AFP/Getty Images)
Boston Deals With Aftermath Of Marathon Explosions
Angelina Ciccantelli (L) and Whitney Kleinert lay flowers at a memorial site at Boylston and Arlington streets along the course of the Boston Marathon on April 16, 2013. (DON EMMERT/AFP/Getty Images)
Boston Deals With Aftermath Of Marathon Explosions
A woman takes a cell phone photograph of a poster on Boylston and Arlington streets on April 16, 2013 in Boston, a few blocks from where two explosions struck near the finish line of the Boston Marathon April 15. (STAN HONDA/AFP/Getty Images)
Boston Deals With Aftermath Of Marathon Explosions
A Boston police officer stands guard at a memorial site at Boylston and Arlington streets along the course of the Boston Marathon on April 16, 2013, a few blocks from where two explosions struck near the finish line of the Boston Marathon on April 15. (DON EMMERT/AFP/Getty Images)
Boston Deals With Aftermath Of Marathon Explosions
Three Boston shirts lay on a barricade at a memorial site at Boylston and Arlington streets along the course of the Boston Marathon on April 16, 2013, a few blocks from where two explosions struck near the finish line of the Boston Marathon on April 15. (DON EMMERT/AFP/Getty Images)
Boston Deals With Aftermath Of Marathon Explosions
Two people lay flowers at a memorial site at Boylston and Arlington streets along the course of the Boston Marathon on April 16, 2013, a few blocks from where two explosions struck near the finish line of the Boston Marathon on April 15. (DON EMMERT/AFP/Getty Images)
Boston Deals With Aftermath Of Marathon Explosions
A man in a Boston Marathon 2013 shirt carries flowers near a memorial site at Boylston and Arlington streets along the course of the Boston Marathon on April 16, 2013, a few blocks from where two explosions struck near the finish line of the Boston Marathon on April 15. (DON EMMERT/AFP/Getty Images)
Boston Deals With Aftermath Of Marathon Explosions
A tube of Bengay, a pain relief medecine, lays nears flowers at a memorial site at Boylston and Arlington streets along the course of the Boston Marathon on April 16, 2013, a few blocks from where two explosions struck near the finish line of the Boston Marathon on April 15. (DON EMMERT/AFP/Getty Images)
Boston Deals With Aftermath Of Marathon Explosions
A man helps transfer flowers at a memorial on Boylston and Arlington streets to an area nearby on April 16, 2013 in Boston, a few blocks from where two explosions struck near the finish line of the Boston Marathon on April 15. (STAN HONDA/AFP/Getty Images)
