The firearms-related death toll in 2014 leapt 56 percent against 2013 figures, with 50 officers killed this year compared to 32 last year, the report said.
Ambushes became the leading circumstance of policemen firearms-related fatalities. Out of 50 officers shot and killed, 15 policemen were fired at ambush, according to the report.
Police have been on alert since two officers Rafael Ramos and Wenjian Liu were shot to death in their patrol car in New York by an African-American man who was mentally ill.
The police have become the center of attention in the United States due to nationwide unrest related to several incidents of police killing unarmed African-Americans.