Police departments on alert after cop killings

Crain's New York reports:

Big-city police departments and union leaders around the country 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 killings of Officers Rafael Ramos and Wenjian Liu on Saturday afternoon in Brooklyn heightened fears about the safety of law enforcement officials nationwide. The gunman, 28-year-old Ismaaiyl Brinsley, had vowed in an Instagram post to put "wings on pigs" as retaliation for the deaths of black men at the hands of white police.

Mr. Brinsley was black; the slain New York Police Department officers were Hispanic and Asian.

The big city update.