According to Bob Orr of CBS News, there is surveillance footage of a yet unidentified man who was placing backpacks inside trash cans on the Boston sidewalk where these explosions occurred. Governor Deval Patrick and Boston Police Commissioner Ed Davis are holding a live press conference, along with the Massachusetts Emergency Management Agency. It has been confirmed that two bombs were detonated 50 to 100 yards apart near the finish line of the Boston Marathon. A third explosion also occurred at the JFK Presidential Library at the University of Massachusetts Boston.
Again, according to Bob Orr of CBS News, there is surveillance footage of a man dropping backpacks into trash cans near the marathon finish line.