The outter perimeter near Massachusetts Avenue and Newbury Street is secured by police after two explosive devices detonated at the finish line of the 117th Boston Marathon on April 15, 2013 in Boston, Massachusetts. Two people are confirmed dead and at least 23 injured after two explosions went off near the finish line to the marathon. (Photo by Alex Trautwig/Getty Images)
Boston Marathon Tragedy
Runners and police gather near Kenmore Square after two bombs exploded during the 117th Boston Marathon on April 15, 2013 in Boston, Massachusetts. Two people are confirmed dead and at least 23 injured after two explosions went off near the finish line to the marathon. (Photo by Alex Trautwig/Getty Images)
Boston Marathon Tragedy
A runner uses his phone as others gather near Kenmore Square after two bombs exploded during the 117th Boston Marathon on April 15, 2013 in Boston, Massachusetts. Two people are confirmed dead and at least 23 injured after two explosions went off near the finish line to the marathon. (Photo by Alex Trautwig/Getty Images)
Boston Marathon Tragedy
Runners gather near Kenmore Square after two bombs exploded during the 117th Boston Marathon on April 15, 2013 in Boston, Massachusetts. Two people are confirmed dead and at least 23 injured after two explosions went off near the finish line to the marathon. (Photo by Alex Trautwig/Getty Images)
Boston Marathon Tragedy
A runner sits near Kenmore Square after two bombs exploded during the 117th Boston Marathon on April 15, 2013 in Boston, Massachusetts. Two people are confirmed dead and at least 23 injured after two explosions went off near the finish line to the marathon. (Photo by Alex Trautwig/Getty Images)
Boston Marathon Tragedy
Runners gather near Kenmore Square after two bombs exploded during the 117th Boston Marathon on April 15, 2013 in Boston, Massachusetts. Two people are confirmed dead and at least 23 injured after two explosions went off near the finish line to the marathon. (Photo by Alex Trautwig/Getty Images)
Boston Marathon Tragedy
People walk near Kenmore Square after two bombs exploded during the 117th Boston Marathon on April 15, 2013 in Boston, Massachusetts. Two people are confirmed dead and at least 23 injured after two explosions went off near the finish line to the marathon. (Photo by Alex Trautwig/Getty Images)
Boston Marathon Tragedy
A woman looks on as runners pass near Kenmore Square after two bombs exploded during the 117th Boston Marathon on April 15, 2013 in Boston, Massachusetts. Two people are confirmed dead and at least 28 injured after at least two explosions went off near the finish line to the marathon. (Photo by Alex Trautwig/Getty Images)
Boston Marathon Tragedy
Runners talk to Boston Police near Kenmore Square after two bombs exploded during the 117th Boston Marathon on April 15, 2013 in Boston, Massachusetts. Two people are confirmed dead and at least 28 injured after at least two explosions went off near the finish line to the marathon. (Photo by Alex Trautwig/Getty Images)
Boston Marathon Tragedy
A runner embraces another woman on the marathon route near Kenmore Square after two bombs exploded during the 117th Boston Marathon on April 15, 2013 in Boston, Massachusetts. Two people are confirmed dead and at least 23 injured after two explosions went off near the finish line to the marathon. (Photo by Alex Trautwig/Getty Images)
Boston Marathon Tragedy
A member of the bomb squad investigates a suspicious item on the road near Kenmore Square after two bombs exploded during the 117th Boston Marathon on April 15, 2013 in Boston, Massachusetts. Two people are confirmed dead and at least 23 injured after two explosions went off near the finish line to the marathon. (Photo by Alex Trautwig/Getty Images)
Boston Marathon Tragedy
Runner John Ounao crying when he finds friends after several explosions rocked the finish of the Boston Marathon in Boston, Massachusetts, on April 15, 2013. At least two people were killed and 22 wounded when two explosions struck near the finish line of the Boston Marathon sparking scenes of panic, police said. The streets were littered with debris and blood and paramedics raced off with stretchers as police locked down the area, witness said. TV footage showed an explosion sending up a white plume of smoke along the sidelines of the race. (Photo credit: John Mottern/AFP/Getty Images)
Boston Marathon Tragedy
Firefighters take postion on Boyltson Street near the finish line after two bombs exploded during the 117th Boston Marathon on April 15, 2013 in Boston, Massachusetts. Two people are confirmed dead and at least 28 injured after at least two explosions went off near the finish line to the marathon. (Photo by Darren McCollester/Getty Images)
Boston Marathon Tragedy
Boston Police guard an area near Kenmore Square after two bombs exploded during the 117th Boston Marathon on April 15, 2013 in Boston, Massachusetts. Two people are confirmed dead and at least 23 injured after two explosions went off near the finish line to the marathon. (Photo by Alex Trautwig/Getty Images)
Boston Marathon Tragedy
A runner reacts near Kenmore Square after two bombs exploded during the 117th Boston Marathon on April 15, 2013 in Boston, Massachusetts. Two people are confirmed dead and at least 23 injured after two explosions went off near the finish line to the marathon. (Photo by Alex Trautwig/Getty Images)
Boston Marathon Tragedy
A member of the bomb squad investigates a suspicious item on the road near Kenmore Square after two bombs exploded during the 117th Boston Marathon on April 15, 2013 in Boston, Massachusetts. Two people are confirmed dead and at least 23 injured after two explosions went off near the finish line to the marathon. (Photo by Alex Trautwig/Getty Images)
Boston Marathon Tragedy
A SWAT team arrives at the corner of Stuart Street and Dartmouth Street after two explosive devices detonated at the finish line of the 117th Boston Marathon on April 15, 2013 in Boston, Massachusetts. Two people are confirmed dead and at least 23 injured after two explosions went off near the finish line to the marathon. (Photo by Darren McCollester/Getty Images)
Boston Marathon Tragedy
Runners listen to directions from a Boston Police officer at the corner of Stuart Street and Dartmouth Street after two explosive devices detonated at the finish line of the 117th Boston Marathon on April 15, 2013 in Boston, Massachusetts. Two people are confirmed dead and at least 23 injured after two explosions went off near the finish line to the marathon. (Photo by Darren McCollester/Getty Images)
