Los Angeles (CNN) -- A former Los Angeles cop with military training waged war with his former colleagues Thursday, killing one.
Jittery police searched a huge swath of southern California -- from San Diego to Los Angeles -- for Christopher Jordan Dorner, a 270-pound former Navy lieutenant with a mighty beef against LAPD officers he claimed ruined his life by forcing him out of his dream job.
The shootings came a day after Irvine, California, police named Dorner a suspect in the double slayings of a woman -- identified by Los Angeles police as the daughter of a retired LAPD officer -- and her fiancé. Dorner blamed the retired officer for bungling his appeal to get his job back, according to a letter he wrote complaining of mistreatment by the LAPD.
Police in Riverside -- where two officers were shot early Thursday -- patrolled with rifles hoisted to their shoulders. Law enforcement in armor patrolled outside LAPD's iconic headquarters. The department put every available resource into guarding people Dorner named as targets.
"I will bring unconventional and asymmetrical warfare to those in LAPD uniform whether on or off duty," Dorner wrote in the letter.
"I never had the opportunity to have a family of my own, I'm terminating yours," he wrote.
In Torrance, California, LAPD officers guarding one of those people opened fire early Thursday morning on a blue pickup truck that resembled the one Dorner is said to be driving, Los Angeles Police Chief Charlie Beck said. The gunfire left two people wounded in what Beck said was a case of mistaken identity.
The truck was a newspaper delivery vehicle, a senior law enforcement source said. The source said Torrance police fired on another blue pickup truck in the city, but no one was injured.
Police have good reason to be fearful, the chief said.
"Of course he knows what he's doing. We trained him," Beck said. "He was also a member of the Armed Forces. It is extremely worrisome and scary, especially to the officers involved."
It all started Sunday when Dorner allegedly killed two people in Irvine, according to police.
Police identified the victims as Monica Quan and her fiancé Keith Lawrence.
Quan, 27, was the daughter of retired Los Angeles police officer Randal Quan, LAPD Officer Tenesha Dobine confirmed to CNN. In his letter, Dorner said Quan had handled his appeal.
Wednesday, police in San Diego say a man who could have been Dorner tried to hijack a boat there. Someone later found a wallet containing Dorner's identification and an LAPD detective's badge near the San Diego airport, according to police.
Then -- around 1:25 a.m. Thursday -- police believe Dorner shot and slightly wounded one of the many Los Angeles police officers being deployed around the region to protect targets named by the former cop.
Officers chased the gunman, who fired on and disabled their car before escaping. Police don't know if the suspect was hurt in the incident, but about 20 minutes later, they say he attacked two police officers sitting at a stop light in the Los Angeles suburb of Riverside.
Beck said the Riverside officers had been "cowardly ambushed."
One of them died, police said.
A good Samaritan picked up one of their police radios and called dispatchers to send help, Riverside police said.
KTLA: Manhunt for former cop after officers shot
In Dorner's letter, provided to CNN by an LAPD source, he complained that he had been railroaded out of the department after reporting police brutality by another officer. He also complained of a continuing culture of racism and brutality in the LAPD.
He said the attacks were "a necessary evil that I do not enjoy but must partake and complete for substantial change to occur within the LAPD and reclaim my name."
After the police department's Board of Rights rejected his appeal, he took the case to court. A judge ruled against his appeal in October 2011, according to court records.
Dorner's writings speak to "a depraved and abandoned mind and heart," Riverside Police Chief Sergio Diaz said in a news conference.
Beck, the Los Angeles police chief, said Thursday that Dorner's case had been "thoroughly reviewed" and he said the department would not apologize to Dorner or clear his name.
KCBS: Riverside officer fatally shot
In the letter, Dorner warned police to "look your wives/husbands and surviving children directly in the face and tell them the truth as to why your children are dead."
Such a chilling warning prompted Los Angeles police to set up 40 protective details in an effort to safeguard people listed in Dorner's letter, Beck said.
He acknowledged it was taxing the department, which has been placed under tactical alert -- meaning all officers must stay on duty.
"It's extremely, extremely manpower intensive," Beck said. "But the safety of my employees, people that come on the job to protect the lives of strangers, is extremely important to me and I will expend whatever resource is necessary."
Dorner is a former U.S. Navy Reserve lieutenant who worked with river warfare units and a mobile inshore undersea warfare unit, among other assignments, according to Pentagon records obtained by CNN. He also provided security on oil platforms in Iraq.
He was rated as a rifle marksman and pistol expert, according to the records. His last day in the Navy was February 1.