April 15, 2013: Two bombs were detonated back to back near the finish line of the Boston Marathon. The bombs exploded at about 2:42 p.m. in the afternoon, one 13 seconds behind the other, as some runners were finishing the race. At least three people were killed, including an 8-year-old boy. More than 170 people were injured. The first explosion happened on Boylston Street close to the finish line. The second blast exploded about 100 yards away. A third explosion occurred an hour after the first two, but it was a controlled explosion by authorities.