The Los Angeles Police Department is ordering officers to ride in pairs because of a warning that street gangs made a pact to "take out" cops after a Baltimore man was fatally injured while in custody.
L.A. officials said they made the call to issue the so-called "blue alert" out of an abundance of caution, and until they can assess how serious the threat is.
In a statement issued earlier Monday, embattled Baltimore police announced they had received a "credible threat" that the Black Guerrilla Family, the Bloods, the Crips and other rivals planned to target officers.
"Law enforcement agencies should take appropriate precautions to ensure the safety of their officers," the Baltimore PD advised, without saying how it learned of the alleged plan.
Police departments across the country were reacting to the warning.
The Connecticut State Police sent out a bulletin to all its troopers, and the Fairfield, Connecticut, police asked the public to report "suspicious activities" to authorities. The San Francisco Police Department said it is taking "tactical precautions," but did not elaborate.
The New Haven, Connecticut, police said it was aware of the alert but did not know of any specific threats in the city.
"Officers in our, and other, departments across the nation are ever watchful for those who'd seek to do us harm. This is a daily awareness regardless of credible threats," they said in a statement.
In Baltimore, seven officers were injured Monday during protests that turned violent following the funeral for Freddie Gray, who died of spinal injuries a week after being arrested.