Timeline: Bomb plots on U.S. soil

world trade center, twin towers, 1993 — MARIA BASTONE/AFP/Getty Images

A bomb in a van explodes in the underground World Trade Center garage in New York City, killing six people and injuring more than 1,000. Five extremists are eventually convicted.

A police photographer adjusts a light at the edge of the crater in an underground parking garage at the World Trade Center Feb. 28, 1993.

April 19, 1995: Oklahoma City

A car bomb parked outside the Murrah Federal Building in Oklahoma City kills 168 people and injures more than 500. It is the deadliest U.S. bombing in 75 years. Timothy McVeigh and Terry Nichols are convicted. McVeigh is executed in 2001 and Nichols is sentenced to life in prison.

Justin Flagg, 7, gets a hug from his father, Lee, as he sits on the trunk of an Oklahoma trooper police car at the site of bombing of the Alfred P. Murrah federal building in downtown Oklahoma City, May, 2, 1995.

Timothy McVeigh, age 27, is led from the Noble County Courthouse in Perry, Okla., April 21, 1995, after being charged with involvement in the bombing of the Alfred P. Murrah Federal Building in Oklahoma City.

July 27, 1996

A bomb explodes at Centennial Olympic Park in Atlanta during the Summer Games, killing two people and injuring more than 100. Eric Robert Rudolph is arrested in 2003. He pleads guilty and is sentenced to life in prison.

The body of a victim lies on the scene of the Olympic Park bombing, July 27, 1996, in Atlanta.

Dec. 14, 1999: Millennium plot

Ahmed Ressam was arrested near the U.S.-Canadian border and convicted of plotting to bomb Los Angeles International Airport at the turn of the millennium. — AP Photo/Canadian Press via Le Journal de Montreal

Al Qaeda-trained terrorist Ahmed Ressam is captured attempting to smuggle explosives across the Canadian border in a rental car, and later convicted in a "Millennium plot" to bomb Los Angeles International Airport on New Year's Day 2000.

Sept. 11, 2001

Four commercial jets are hijacked by 19 al Qaeda militants and used as suicide bombs, bringing down the two towers of New York City's World Trade Center and crashing into the Pentagon. Nearly 3,000 people are killed in New York, Washington and Pennsylvania.

People walk in the street in the area where the World Trade Center buildings collapsed, Sept. 11, 2001.

A survivor sits outside the World Trade Center after two planes hit the building, Sept. 11, 2001, in New York City.

The rubble of the World Trade Center smolders after the Sept. 11 attack.

Smoke comes out from the west wing of the Pentagon building, Sept. 11, 2001, in Arlington, Va., after a plane crashed into the building and set off a huge explosion.

Cynthia Salter, who lost her sister, Catherine, in the South Tower on 9/11 pauses in front of the Wall of Names at the Flight 93 National Memorial, Sept. 11, 2012, in Shanksville, Pa.

Dec. 22, 2001: Shoe bomber

Convicted shoe bomber Richard Reid, age 28, is shown in this Dec. 24, 2001, police photograph. With the horror of Sept. 11 still fresh in the minds of the American public, the self-confessed al Qaeda member created another scare from the sky. On Dec. 22, 2001, Reid boarded American Airlines Flight 63 from Paris to Miami with a homemade bomb concealed in his shoe. He tried to blow up the jet but failed to light the fuse before being subdued by passengers and the flight crew. Reid was convicted of all charges against him and is currently serving a life sentence at a Colorado prison.

The passport of failed shoe bomber Richard Reid is displayed alongside the matches he used to try and ignite the fuse of his shoes as well as vials of tranquilizers that were used to sedate him, as part of a 2011 exhibit at the Newseum in Washington, D.C.

A courtroom drawing depicts U.S. Federal judge William Young sentencing shoe bomber Richard Reid to life in prison, Jan. 30, 2003, in Boston.

The shoes used in the failed attempt to blow up an airplane by shoe bomber Richard Reid are displayed alongside an FBI model of the shoe filled with explosives as part of a 2011 exhibit at the Newseum in Washington, D.C.

Dec. 25, 2009: Underwear bomber

The so-called "underwear bomber," Nigerian Umar Farouk Abdulmutallab, is subdued by passengers and crew after trying to blow up an airliner heading from Paris to Detroit using explosives hidden in his undergarments. Abdulmutallab, seen here in a photo released by the U.S. Marshal's Service, is sentenced to life in prison.

Umar Farouk Abdulmutallab's alleged underwear bomb — FBI

Remnants of the underwear and explosive device allegedly carried by Umar Farouk Abdulmutallab aboard Delta Flight 253.

Umar Farouk Abdulmutallab, charged with trying to detonate an explosive device on an airplane, is seen at a school in Lome, Togo, in this undated photo provided by Mike Rimmer.

Nancy Edmonds, Umar Farouk Abdulmutallab — AP Photo/Jerry Lemenu

In a courtroom sketch, Umar Farouk Abdulmutallab is sentenced to life in prison by U.S. District Judge Nancy Edmonds in federal court in Detroit, Feb. 16, 2012.

May 1, 2010: Times Square plot

Pakistani immigrant Faisal Shahzad leaves an explosives-laden SUV in New York's Times Square, hoping to detonate it on a busy night. Street vendors spot smoke coming from the vehicle and the bomb is disabled. Shahzad is arrested as he tries to leave the country and is sentenced to life in prison.

A diagram of the car bomb of the Times Square attempted bombing is displayed during a press briefing in Washington, D.C., May 4, 2010.

April 15, 2013: Boston Marathon bombings

4/15: Bombs explode at the Boston Marathon; Coordinated explosions suggest some expertise — CBS News

Two bombs explode in the packed streets near the finish line of the Boston Marathon, killing three people and injuring more than 175.

Police officers react to a second explosion at the finish line of the Boston Marathon in Boston, April 15, 2013.

Police officers react to a second explosion at the finish line of the Boston Marathon in Boston, April 15, 2013.

In this photo provided by The Daily Free Press and Kenshin Okubo, people react to an explosion at the 2013 Boston Marathon in Boston, April 15, 2013.