UPDATE: The Boston Police say it appears that the Boston Library situation was a fire in the new building boiler room, not an explosion. Stay tuned.
Edward Davis, Boston Police Commissioner has just said there is a third explosion after the first two near the end of the track for the Boston Marathon. The third explosion was at JFK Library in Boston [some distance away from the Boston Marathon finish line explosions].
Governor Deval Patrick is onsite, and hosptials say 2 dead, over 100 [updated] injured with shrapnel and glass wounds and amputations from the force of the explosion, 6 critical, it is said. All victims have been transported from the scene to hospitals.
The Police Commissioner and the Governor are asking people in Boston to stay in their homes, not congregate in groups. Air transport has been grounded from several airports if their destination was into Boston.
Next briefing will be in two hours.
Federal Investigators are on the ground in Boston
President Obama is in telephone communication with Boston and Massachusetts governor, mayor and other officials.
Thousands of spectators, including many children, were on both sides of the Marathon path as the bombs went off.