Updated, 4:18 p.m., E.T. Former police chief William Bratton has confirmed that the explosions (there were several) were the result of bombs that had been left in backpacks near the finish line. Several failed to detonate. This has now been ruled an act of terrrorism. The original story follows:
The 117th annual Boston Marathon, which was run today, was marred by bloodshed, when an explosion of indeterminate origin was reported at the finish line. Three people have been confirmed dead and between 20 and 30 were seriously injured. Many of the victims lost limbs from the violent blast, according to Reuters.
The explosion occurred as thousands of runners finished the 117th running of the Boston Marathon, with crowds watching and cheering at the finish.
Mike Mitchell of Vancouver, Canada, a runner who had finished the race said he was looking back at the finish line and saw a “massive explosion.” Smoke rose 50 feet in the air, he said. People began running and screaming after hearing the noise.
Updates to this story will follow as new information becomes available.