Christopher Dorner was also charged with the attempted murder of another Riverside officer and two Los Angeles Police Department officers, Riverside County District Attorney Paul Zellerbach said.

The LAPD officers and the Riverside officers were fired on in two separate shootings early Thursday after Dorner, 33, became the target of a manhunt following the killing in Irvine of a former LAPD captain’s daughter and her fiance the previous weekend.

“By both his words and conduct, he has made very clear to us that every law enforcement officer in Southern California is in danger of being shot and killed,” Zellerbach said at a news conference guarded by four officers armed with rifles.

Authorities obtained a no-bail arrest warrant, which allows Dorner to be apprehended anywhere, Zellerbach said.

Meanwhile, U.S. border inspectors warned that the search for Dorner has created unusually heavy traffic backups at California border crossings into Mexico.

Baja California state police agents were given photographs of Dorner and warned to consider him armed and extremely dangerous.

Authorities said they were investigating more than 700 tips after offering a $1 million reward for information leading to the arrest of Dorner, who is believed to have written a Facebook rant against those he held responsible for ending his LAPD career five years ago, when a department board determined that he falsely claimed another officer had kicked a suspect.

“Some people are from his past, some people think they saw him yesterday, some think they have information about where he will be,” police Lt. Andrew Neiman said.

Police and city officials believe the reward, raised from both public and private sources, will encourage the public to stay vigilant.

“Now it’s like the game show ‘Who Wants to be a Millionaire,’” said Anthony Burke, supervisory inspector for the U.S. Marshals regional fugitive taskforce. “Instead of one contestant, we’ve got 100,000, and there’s only one question you have to answer. All they have to answer is where he’s at, and we can take it from there.”

Meanwhile, LAPD resources remained strained as the department deployed 50 protection details to guard officers and their families who were deemed possible targets.

The charges filed in Riverside County did not include the Irvine killings.

Monica Quan, a former LAPD captain’s daughter, and her fiance were found shot dead Feb. 3 in a car in the parking structure of their condominium. Dorner was named as the suspect in those killings on Wednesday.

A federal agent who requested anonymity because of the ongoing investigation said officials had determined a call telling Quan’s father, Randal Quan, that he should have done a better job of protecting his daughter was a prank.

The violence escalated early Thursday in Riverside County, when police say Dorner got into a shootout withpolice in Corona, grazing an LAPD officer’s head with a bullet before escaping. Authorities believe Dorner then used a rifle to ambush the two Riverside police officers, killing one and seriously wounding another. The slain officer was identified as Michael Crain, 34.

Late last week, the manhunt focused on the Big Bear area of the San Bernardino Mountains, where authorities found Dorner’s burned-out truck with weapons and camping gear inside.

A greatly reduced force of 30 deputies searched there for the fifth day on Monday.