In response to the fatal shooting of five cops in Dallas, police departments across the country are changing tactics to protect their officers, and the changes start with officers teaming up on patrols.

Washington D.C. Police Chief Cathy Lanier said at a news conference Friday morning that officers are shaken by the events in Dallas, but they have to carry on their mission. She said officers paired up starting on the midnight shift and they’ll stay that way until further notice. Lanier said the police department also has increased security around building and lots.

“Looking at the type of attack that happened in Dallas, a two-man car, a four-man car, a 10-man car, isn’t going to make much of a difference. But it makes the officers feel much safer,” the chief said, according to the Washington Examiner.

Boston police will patrol in groups of two in the wake of the Dallas sniper attack which also wounded seven officers and two civilians, according to the Boston Herald.

“In light of the tragedy in Dallas and in the best interest of officer safety, all BPD patrols will be conducted by two-officer units,” Boston PD said on Twitter.

All NYPD cops were ordered to patrol in pairs—and even take their lunch break with their partner—in a department-wide memo Friday, the Daily News reported.

“There are to be no solo assignments citywide,” the memo stated.

The memo also reminded cops to think tactically and to remain alert especially when being approached by members of the public, ABC 7 reported.

The police chief of Burlington, Vermont, Brandon del Pozo told the Burlington Free Press that when he woke up Friday morning to news of the Dallas shootings, “I was literally shaking. It was beyond words.”

Del Pozo said he ordered his officers to conduct foot patrols in pairs until the threat of a copycat attack diminishes.

The Las Vegas Metro Police Department said its officers normally ride in patrol cars alone, but will be doubled up until further notice.

Sgt. Jeff Clark says officers are mindful of the outrage and frustration over fatal police shootings of black men in Louisiana and Minnesota this week. But he says policing is being “bashed as a profession.”

In one New York City suburb cops were ordered to pair up in patrol vehicles.

The Nassau County Police Department on Long Island said it will also be intensifying patrols in areas of public gatherings and certain locations to ensure the safety of the public and officers, Patch reported.

The Associated Press contributed to this report.