Boston Marathon bombings

Runners continue to run towards the finish line of the Boston Marathon as an explosion erupts near the finish line of the race in this photo exclusively licensed to Reuters by photographer Dan Lampariello after he took the photo in Boston, Massachusetts, April 15, 2013. Two simultaneous explosions ripped through the crowd at the finish line of the Boston Marathon on Monday, killing at least two people and injuring dozens on a day when tens of thousands of people pack the streets to watch the world famous race. REUTERS EXCLUSIVE REUTERS/Dan Lampariello (UNITED STATES - Tags: CRIME LAW SPORT ATHLETICS TPX IMAGES OF THE DAY ) MANDATORY CREDIT

BOSTON - APRIL 15: Police officers with their guns drawn hear the second explosion down the street. The first explosion knocked down a runner at the finish line of the 117th Boston Marathon. (Photo by John Tlumacki/The Boston Globe via Getty Images)

This Monday, April 15, 2013 photo provided by Bob Leonard shows third from left, Tamerlan Tsarnaev, who was dubbed Suspect No. 1 and second from left, Dzhokhar A. Tsarnaev, who was dubbed Suspect No. 2 in the Boston Marathon bombings by law enforcement. This image was taken approximately 10-20 minutes before the blast. (AP Photo/Bob Leonard)

ATTENTION EDITORS - VISUAL COVERAGE OF SCENES OF DEATH AND INJURY Wounded spectators lie injured following an explosion at the Boston Marathon in Boston, Massachusetts, April 15, 2013. Two simultaneous explosions ripped through the crowd at the finish line of the Boston Marathon on Monday, killing two people and injuring dozens on a day when tens of thousands of people pack the streets to watch the world famous race. Picture taken April 15, 2013. REUTERS/MetroWest Daily News/Ken McGagh/Handout (UNITED STATES - Tags: CRIME LAW SPORT ATHLETICS TPX IMAGES OF THE DAY) FOR EDITORIAL USE ONLY. NOT FOR SALE FOR MARKETING OR ADVERTISING CAMPAIGNS. THIS IMAGE HAS BEEN SUPPLIED BY A THIRD PARTY. IT IS DISTRIBUTED, EXACTLY AS RECEIVED BY REUTERS, AS A SERVICE TO CLIENTS. NO ARCHIVES. MANDATORY CREDIT

An emergency responder and volunteers, including Carlos Arredondo in the cowboy hat, push Jeff Bauman in a wheel chair after he was injured in an explosion near the finish line of the Boston Marathon Monday, April 15, 2013 in Boston. At least three people were killed, including an 8-year-old boy, and more than 170 were wounded when two bombs blew up seconds apart. (AP Photo/Charles Krupa)

BOSTON - APRIL 15: (EDITOR'S NOTE: THIS IMAGE CONTAINS GRAPHIC CONTENT) Bystanders help an injured woman at the scene of the first explosion on Boylston Street near the finish line of the 117th Boston Marathon. The Boston Globe has identified the woman in this photo as Sydney Corcoran, a 17-year-old senior at Lowell High School. She survived the blasts.(Photo by John Tlumacki/The Boston Globe via Getty Images)

Scott Turner (C) is hugged by friends as he weeps at a vigil for bomb victims a day after two explosions hit the Boston Marathon, in Boston, Massachusetts April 16, 2013. The twin blasts on Monday killed three people including an 8-year-old boy and injured 176 others, some of whom were maimed by bombs packed with ball bearings and nails. REUTERS/Adrees Latif (UNITED STATES - Tags: CRIME LAW CIVIL UNREST TPX IMAGES OF THE DAY)

BOSTON, MA - APRIL 16: 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. The twin bombings, which occurred near the marathon finish line, resulted in the deaths of three people while hospitalizing at least 128. The bombings at the 116-year-old Boston race, resulted in heightened security across the nation with cancellations of many professional sporting events as authorities search for a motive to the violence. (Photo by Spencer Platt/Getty Images)

BOSTON - APRIL 16: An MP with the 747 checks an ID on Massachusetts Avenue on April 16, 2013 in Boston, Massachusetts. Security is especially tight in the city of Boston after two explosions went off near the finish of the Marathon, killing three people and injuring at least 141 others. (Photo by Darren McCollester/Getty Images)

Investigators comb through the scene of one of the blast sites of the Boston Marathon explosions, Wednesday, April 17, 2013, in Boston. (AP Photo/Julio Cortez)

This photograph obtained April 16, 2013 courtesy of the Federal Bureau of Investigation (FBI) shows the remnants of a pressure cooker the FBI says was part of one of the bombs used during the Boston Marathon on April 15, 2013. US investigators have told how two suspected pressure cooker bombs sprayed nails and metal pellets into Boston marathon crowds, killing three people and injuring more than 180. But with no claim of responsibility made and police not committing to blaming foreign or domestic militants, Boston harbored widespread questions about the perpetrators as the city and the nation paid tribute to the dead. AFP PHOTO / FBI == RESTRICTED TO EDITORIAL USE / MANDATORY CREDIT: \"AFP PHOTO / FBI\" / NO SALES / NO MARKETING / NO ADVERTISING CAMPAIGNS / DISTRIBUTED AS A SERVICE TO CLIENTS ==-/AFP/Getty Images

Officials secure an area in Watertown, Mass., Friday, April 19, 2013. Reports of explosives being detonated and police are telling reporters to turn off their cell phones. Dozens of officers and National Guard members are in Watertown, where television outlets report that gunfire and explosions have been heard. (AP Photo/Julio Cortez)

CAMBRIDGE, MA - APRIL 19: The Boston area is under lockdown as as a manhunt is underway for a suspect in the terrorist bombing of the 117th Boston Marathon earlier this week. The Mass. Avenue bridge has only a few pedestrians crossing. (Photo by Jonathan Wiggs/The Boston Globe via Getty Images)

A police officer evacuates a shoeless man holding a child as members of law enforcement conduct a search for a suspect in the Boston Marathon bombings, Friday, April 19, 2013, in Watertown, Mass. Two suspects in the Boston Marathon bombing killed an MIT police officer, injured a transit officer in a firefight and threw explosive devices at police during a getaway attempt in a long night of violence that left one of them dead and another still at large Friday, authorities said as the manhunt intensified for a young man described as a dangerous terrorist. (AP Photo/Matt Rourke)

SWAT teams enter a suburban neighborhood to search an apartment for the remaining suspect in the Boston Marathon bombings in Watertown, Massachusetts April 19, 2013. Police killed one suspect in the Boston Marathon bombing during a shootout and were engaged in a house-to-house search for a second man on Friday in the Boston suburb of Watertown after a bloody night of shooting and explosions in the city's streets. REUTERS/Jessica Rinaldi (UNITED STATES - Tags: CIVIL UNREST CRIME LAW)

A woman carries a girl from their home as a SWAT team searching for a suspect in the Boston Marathon bombings enters the building in Watertown, Mass., Friday, April 19, 2013. Two suspects in the Boston Marathon bombing killed an MIT police officer, injured a transit officer in a firefight and threw explosive devices at police during their getaway attempt in a long night of violence that left one of them dead and another still at large Friday, authorities said as the manhunt intensified for a young man described as a dangerous terrorist. (AP Photo/Charles Krupa)

An aerial infrared image shows the outline of Dzhokhar Tsarnaev in a boat during the manhunt in Watertown, Massachusetts, April 19, 2013, courtesy of the Massachusetts State Police. A telephone call from a resident led police to the boat where the suspect, identified as Dzhokhar Tsarnaev, was hiding and a police helicopter detected a heat signal that confirmed his presence there, said Boston Police Commissioner Ed Davis. REUTERS/Massachusetts State Police/Handout (UNITED STATES - Tags: CRIME LAW TPX IMAGES OF THE DAY) FOR EDITORIAL USE ONLY. NOT FOR SALE FOR MARKETING OR ADVERTISING CAMPAIGNS. THIS IMAGE HAS BEEN SUPPLIED BY A THIRD PARTY. IT IS DISTRIBUTED, EXACTLY AS RECEIVED BY REUTERS, AS A SERVICE TO CLIENTS

In this Friday, April 19, 2013 Massachusetts State Police photo, 19-year-old Boston Marathon bombing suspect Dzhokhar Tsarnaev raises his hand from a boat at the time of his capture by law enforcement authorities in Watertown, Mass. (AP Photo/Massachusetts State Police, Sean Murphy)

A police officer and a woman react to news of the arrest of one of the Boston Marathon bombing suspects, Friday, April 19, 2013, in Boston. Boston Marathon bombing suspect Dzhokhar Tsarnaev was captured in Watertown, Mass. The 19-year-old college student wanted in the bombings was taken into custody Friday evening after a manhunt that left the city virtually paralyzed and his older brother and accomplice dead. (AP Photo/Julio Cortez)

Neighbors use cameras to record images of the boat at 67 Franklin St. where Dzhokhar Tsarnaev, the surviving suspect in the Boston Marathon bombings, was hiding inside in Watertown, Massachusetts, April 19, 2013. Boston Police said on Friday they have taken custody of the second suspect, Dzhokhar Tsarnaev, and are sweeping the suburban Boston neighborhood where he was captured after a massive manhunt. REUTERS/Lucas Jackson (UNITED STATES - Tags: CRIME LAW)

A moment of silence in honor of the victims of the Boston Marathon bombing is observed on Boylston Street near the race finish line, exactly one week after the tragedy, Monday, April 22, 2013, in Boston, Mass. (AP Photo/Robert F. Bukaty)