Third Explosion Possibly Unrelated

A third explosion in Boston was confirmed Monday by Boston Police Commissioner Edward Davis at a press conference briefing reporters on the tragedy at the Boston Marathon. Davis said the third explosion occurred at the JFK Library at roughly 4:30 p.m., and as such the situation is being treated as “an ongoing event.” But a spokeswoman from the police department and library officials later said over Twitter that, as was first reported, the fire began in the library's mechanical room and was probably not related to the bombings. Investigators are seeking further information.