The incidents come as tensions in the city are on the rise, and a jury prepares to begin deliberating in the trial of two black men accused of attempting to murder a white lorry driver during the Los Angeles riots in 1992.
The outcome of the hearing is considered critical, largely because of the treatment of Laurence Powell and Stacey Koon, the two officers in the King beating case, whose 30-month prison sentences were widely condemned as too lenient. The two men are still free, pending an appeal.
This week the Los Angeles Police Department (LAPD) received an anonymous fax entitled 'Letter of Warning', addressed to 'all white LAPD Officers', threatening to kill a white officer every day until Koon and Powell are jailed. The following day gunmen ambushed an unmarked police car in South Central Los Angeles, and seriously wounded an officer. The next night officers came under fire in the city's Venice area, without injury.
Although the police have not established a link between the threatening fax and the incidents, the city's chief of police, Willie Williams, has ordered tighter security measures, including placing a minimum of two officers in patrol cars.