On April 15, 2013, two explosions occurred near the finish line of the Boston Marathon, killing three people and injuring over 200. An unprecedented manhunt was launched to find the perpetrators, one of whom was killed and the other was taken into custody.

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.
John Tlumacki/The Boston Globe via Getty Images