The FBI says two out of three law enforcement officers who were slain in the line of duty last year were wearing body armor at the time they were killed.
According to preliminary figures, 72 law enforcement officers were killed in 2011, 16 more than were slain in 2010. Of the 72 killed, 49 were wearing body armor.
Among the most frequent circumstances in police killings included ambushes, traffic pursuits and being attacked while attempting other arrests.
Fifty law enforcement officers were killed in accidents last year, down by 22 from the 72 officers who were accidentally killed in 2010.