A police officer holds a shotgun as an ambulance heads down Franklin Road to the scene of the arrest of a suspect of the Boston Marathon bombings in Watertown, Mass., Friday, April 19, 2013. Two ... more 
A police officer holds a shotgun as an ambulance heads down Franklin Road to the scene of the arrest of a suspect of the Boston Marathon bombings in Watertown, Mass., Friday, April 19, 2013. Two suspects in the Boston Marathon bombing killed an MIT police officer, injured a transit officer in a firefight and threw explosive devices at police during their getaway attempt. (AP Photo/Charles Krupa) less 
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Associated Press | Photo By Charles Krupa
Sat, Apr 20, 2013 9:36 AM EDT