Report of BOSTON MARATHON EXPLOSION

By Erin McClam, Staff Writer, NBC News

With thousands of runners still on the course, two bombs exploded near the finish line of the Boston Marathon; killing three people, injuring at least 113.

This turning the city’s most celebrated event into a grisly spectacle of shattered glass, blood and screams.

Minutes later, law enforcement officials said that an 8-year-old child was one of the dead. Video from the scene showed two blasts about 20 seconds apart just off the course at the finish. White smoke rose, barriers flew, and throngs of people who had gathered to cheer the runners turned and fled in terror.