First responders rush to where two explosions occurred along the final stretch of the Boston Marathon on Boylston Street in Boston, Massachusetts, U.S., on Monday, April 15, 2013. Two powerful explosions rocked the finish line area of the Boston Marathon near Copley Square and police said many people were injured. Photographer: Kelvin Ma/Bloomberg

Boston Marathon Bombings

On April 15, 2013, at approximately 2:45 p.m., two bombs went off in succession near the finish line of the Boston Marathon. The timing of the bombs coincided with when the majority of the runners would be crossing the finish line. Hours after the explosions, the Boston, state and federal governments were investigating but were still unsure as to who was responsible for the attacks. Meanwhile, several undetonated bombs were found nearby, leading the city to shut down use of cellular phones so that any remaining explosives could not be detonated remotely. Within hours of the incident, three people had died and over 100 were receiving medical attention.