Boston Globe / The Boston Globe via Getty Images
A second explosion goes off, rear, as a runner was blown to the ground by the first explosion near the finish line of the 117th Boston Marathon.
By Erin McClam, Staff Writer, NBC News
Editor's Note: The image below is graphic and may be disturbing for some viewers.
Two explosions, described by race organizers as bombs, went off near the finish line of the Boston Marathon on Monday as runners completed the course and thousands cheered them on. At least two people were killed and 23 injured, police said.
Video from the finish line showed an enormous cloud of white smoke, and about 20 seconds between the blasts. The explosions were strong enough to cause at least one runner to collapse, and emergency personnel carried bloody spectators away. A witness said that she saw people’s legs blown off.