Law enforcement in Boston, New York, Los Angeles, Chicago and New Orleans are on high alert after three officers were fatally shot on Sunday morning on Airline Highway.

In New York City, the police department told personnel that all officers should patrol and even take breaks in pairs, effective immediately until further notice.

"There are to be no solo foot posts citywide," the NYPD message said. "All uniform members of service shall arrive and remain on post together. All meals and personal breaks will also be taken in pairs. If the assigned post is considered integral to your command operations and you feel it should not be left unmanned during meal breaks, have that post back-filled. Police officers on patrol should maintain a heightened level of awareness."

NYPD also said that the station house security would be mandatory until further notice and all security would have two officers at a time as well.

The Boston Police Department along with Chicago Police Department were also ordered to patrol in pairs.

In Los Angeles, the police chief ordered security enhancements, but the police department requires all cops to work in pairs when responding to calls or crimes in progress.

New Orleans Police officers were also told to respond to call with no less that two officers and two police units on the scene.

"This is a tough time, we'll feel the effects of it for a while, Harrison said. "What they're experiencing, we're experiencing here emotionally. These officers need to feel safe. This will last until we feel we don't need it anymore."

Law enforcement officers were already on high alert in the wake of the shooting death of Alton Sterling, a black man who was shot and killed by two BRPD officers on July 5. Many organized protests and there was even a call to "purge' cops in Baton Rouge.