Scenes from Boston bombing manhunt
A look at the past 24 hours.
STFOfficials search an area on Arsenal Street in Watertown, Mass., Friday, April 19, 2013, as they search for an individual believed to be responsible for the Boston Marathon explosions. The two suspects in the Boston Marathon bombing killed an MIT police officer and hurled explosives at police in a car chase and gun battle overnight that left one of them dead and his brother on the loose, authorities said Friday. (AP Photo/Matt Rourke)