Toronto Police Association President Mike McCormack says anti-police sentiment currently circulating around the globe is putting lives of police officers at risk and can play a factor in destabilizing communities.

Big-city police departments and union leaders around the U.S. are warning the rank and file to wear bulletproof vests and avoid making inflammatory posts on social media in the days after a man ambushed two officers and shot them to death inside their patrol car.

The New York Police Department says a gunman who ambushed two officers in their car told two passers-by to "watch what I'm going to do."