Thousands of mourners -- including MIT students, faculty and staff, and law enforcement officials from across the nation -- have paid their respects to a campus police officer who authorities say was ambushed in his cruiser by the Boston Marathon bombers.

Memorial Service at MIT (Mario Tama, Getty Images)

Speaking at the memorial today at the school's Cambridge campus, Vice President Joe Biden referred to the bombing suspects as "two twisted, perverted, cowardly knockoff jihadis."

Biden told the parents of slain officer Sean Collier that he hopes they find some solace in their extreme grief through today's large memorial service in their son's honor.


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