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In this image provided by the Irvine, Calif., Police Department via The Orange County Register, former Los Angeles police officer Christopher Jordan Dorner is shown. Dorner is a suspect in the killings of Monica Quan and her fiance, Keith Lawrence, who were found shot to death in their car at a parking structure Sunday night.

LOS ANGELES (AP) -- A former Los Angeles police officer sought for two weekend killings -- and who threatened to kill police -- is a suspect in an overnight shooting in nearby Riverside that killed one officer and critically wounded another, police said Thursday.

The shooting happened early Thursday morning in the Los Angeles suburb of Corona. The wounded officer is in surgery. A third officer suffered a graze wound.

Two Newton station officers on security duty in the same area were also involved in a shooting overnight, but they weren't hurt, police said.

Former Los Angeles police officer Christopher Jordan Dorner is the suspect who's wanted in the killings of Monica Quan and her fiancé, Keith Lawrence, who were found shot to death in their car at a parking structure Sunday night, Irvine police Chief David L. Maggard said at a news conference Wednesday night.

Dorner, 33, implicated himself in the killings with a multi-page "manifesto" that he wrote that included threats against several people, including members of the LAPD, police said. They gave no further details on the document or its contents.

Autopsies showed that Quan and Lawrence were killed by multiple gunshot wounds in the parking structure at their condominium in Irvine, Orange County sheriff's spokesman Jim Amormino said earlier Wednesday.

Quan, 28, was an assistant women's basketball coach at Cal State Fullerton. Lawrence, 27, was a public safety officer at the University of Southern California.

The killings brought mourning and disbelief at three college campuses, Fullerton, USC, and Concordia University, where the two met when they were both students and basketball players.

Police do not know Dorner's whereabouts, and authorities were seeking the public's help in finding him.

"We have strong cause to believe Dorner is armed and dangerous," Maggard said, adding that the LAPD and FBI are assisting in the case.

Police said the U.S. Navy reservist may be driving a blue 2005 Nissan Titan pickup truck. His last known address was in La Palma in northern Orange County near Fullerton.

Dorner was with the department from 2005 until 2008, when he was fired for making false statements.

Quan's father, a former LAPD captain who became a lawyer in retirement, represented Dorner in front of the Board of Rights, a tribunal that ruled against Dorner at the time of his dismissal, LAPD Capt. William Hayes told The Associated Press Wednesday night.

Randal Quan retired in 2002. He later served as chief of police at Cal Poly Pomona before he started practicing law.

According to documents from a court of appeals hearing in October 2011, Dorner was fired from the LAPD after he made a complaint against his field training officer, Sgt. Teresa Evans. Dorner said that in the course of an arrest, Evans kicked suspect Christopher Gettler, a schizophrenic with severe dementia.

Following an investigation, Dorner was fired for making false statements.

Richard Gettler, the schizophrenic man's father, gave testimony that supported Dorner's claim. After his son was returned on July 28, 2007, Richard Gettler asked "if he had been in a fight because his face was puffy" and his son responded that he was kicked twice in the chest by a police officer.