A massive manhunt for a former Los Angeles officer suspected of targeting police and their families and leaving three people dead swept across Southern California on Thursday, with law enforcement officials ending the day focused on a remote area in Big Bear.

Police say Chris-topher Jordan Dorner, driven by an apparent grudge against law enforcement, shot and killed one officer and wounded two others Thursday, shortly after he was identified as the prime suspect in the slaying of a daughter of a former Los Angeles Police Department captain and her fiance.

Despite a large-scale search that encompassed at least five counties and stretched from the coast to the mountains, Dorner was at large late Thursday and considered armed and dangerous.

Officers aided by helicopters were expected to search a wooded area near Big Bear Lake overnight, after Dorner’s abandoned, burned pickup was found in the area earlier in the day. The search was slowed by plummeting temperatures and snowfall that was expected to increase into the night.

“This complex and violent investigation has led to this mountain,” LAPD Assistant Chief Michel Moore said from a command center at the base of the Bear Mountain ski resort.

Meanwhile, the intense search also resulted in police shooting two innocent people in Torrance after mistaking a vehicle they were driving as belonging to Dorner.

THE SUSPECT

Dorner was believed to be targeting former colleagues from LAPD after leaving behind an online manifesto and naming several officials he blamed as part of a corrupt department, and bringing about the end of his career in law enforcement. After the killing of a Riverside police officer early Thursday morning, in what authorities described as a “cowardly ambush,” law enforcement officials said it was clear all police officers were a target.

“He has made it clear he considers police officers and their families fair game for his assaults,” Riverside Police Chief Sergio Diaz said.

Irvine police Wednesday night named Dorner, 33, as their prime suspect in the killing of a college basketball coach and her fiance Sunday. Monica Quan and Keith Lawrence were found shot and killed in an Irvine parking structure by their home.

Quan is the daughter of a retired police captain, one of several LAPD officials named in Dorner’s manifesto.

“Self preservation is no longer important to me. I do not fear death as I died long ago on 1/2/09,” Dorner wrote, referring to the day he was fired from the force. “I was told by my mother that sometimes bad things happen to good people.”

Police believe Dorner attempted to steal a boat at gunpoint in San Diego about 8:30 p.m. Wednesday but failed when a rope became tangled in the propeller.

Instead of heading toward Mexico, Dorner is suspected of driving to Corona about 1:25 a.m. Thursday. LAPD officers were also headed to the area for a protective detail, one of about 40 assignments issued by the department after discovering the manifesto. The officers were tipped about a vehicle matching the description of Dorner’s and began to follow it. Dorner is suspected of firing into the patrol car. The officers returned fire, but Dorner fled.

About 20 minutes later in the city of Riverside, Dorner is accused of driving toward a Riverside police patrol vehicle stopped at an intersection and opening fire on the two officers inside.

A 34-year-old officer was fatally shot, Diaz said. A 27-year-old officer was critically injured but expected to recover. Police declined to release the officers’ names for their protection.

ON THE MOVE

Since the first killings Sunday, Dorner is believed to have moved constantly, driving a 2005 Nissan Titan.

Law enforcement officials said Dorner may have switched license plates to evade detection. A pickup similar to Dorner’s was sent to an impound yard in Poway by Irvine crime scene investigators, said Lt. Julia Engen of the Irvine Police Department. The investigators are looking into the possibility that Dorner stole the license plates from the pickup and swapped them onto his own vehicle.

Because of Dorner’s training as an LAPD officer and a reservist for the U.S. Navy, the manhunt has posed additional risks for authorities. Los Angeles and Irvine police said they were making changes to their usual deployment for officer safety.

“Of course he knows what he’s doing; we trained him,” said LAPD Chief Charlie Beck during a news conference Thursday. “He was also a member of the armed forces.”

Dorner left the Navy last week, and officials did not have a reason for his resignation.

The frantic search for him is believed to have also led to the shooting of two people in Torrance, where officers were on their way for a protective detail, Beck said.

The officers were approaching a truck with a similar description and no lights when they opened fire on the two female passengers, Beck said.

“Tragically, we believe this is a case of mistaken identity,” Beck said.

One of the passengers suffered minor injuries and was expected to be released Thursday. The second was shot twice and is stable.

But the attacks have left law enforcement officials across the state shaken and looking into all possible leads for Dorner.

“It’s extremely worrisome and scary, especially to the police officers involved,” Beck said. “Imagine going about your workday having to worry about this.”

Police agencies have been placed on alert throughout Kern, Santa Barbara, San Bernardino, Ventura, San Diego, Imperial, Los Angeles, Orange and Riverside counties, officials said.

“Everybody seems to be a target right now,” Engen said.

A MOUNTAIN SEARCH

By Thursday afternoon, authorities confirmed that Dorner’s truck had been located near Big Bear Lake by officers responding to reports of a burning vehicle.

More than 100 law enforcement officers from numerous agencies joined in an effort to track Dorner in the nearby wilderness and to check door to door at residences.

Officials say the area where they found his burnt pickup is remote. While they did not directly say the tracks are Dorner’s, the markings are believed to be his, given it was his vehicle and the remote site.

“We are assuming he is still in the area,” San Bernardino County Sheriff John McMahon said.

There were no reports of cars being stolen in the area, McMahon said, and no indications of gunshots being fired. Officials declined to say whether weapons were found in the charred pickup.

“He could be anywhere at this point,” McMahon added.

Law enforcement agencies converted the base of the Bear Mountain ski resort into a command post for their manhunt, as nearby ski lifts sat idle.

SWAT officers walked amid parked armored vehicles within the large parking lot behind Wolf Creek Estates, a community near the base of the resort.

The pickup sat hitched to a tow truck, reduced to a hulk of iron, its tires ripped off and its rims and truck body twisted.

The vehicle was to be processed at the crime lab in San Bernardino County, with Irvine, Riverside and LAPD helping investigate the truck.

About three hours before law enforcement officials held a midday news conference in Riverside, Big Bear resident Dean Johnson said his attention was attracted by a helicopter above the ski resort. He works as a computer programmer from his home, which abuts the resort.

SWAT officers scrambled out of the helicopter around 9:15 a.m. at the Moonridge Golf Course, Johnson said. He thought they were practicing some drills, and he didn’t initially connect it to Dorner.

“I was really surprised,” he said of learning Dorner might be around his neighborhood. “I almost thought it was a false lead.”

Johnson, who has lived there for 13 years, was walking his dogs past a row of media trucks. He said he was not worried about the search for Dorner.

“They haven’t caught him, right?” he said. “I will lock my doors tonight. Normally, I don’t.”

Word that Dorner may be in the area left some Big Bear residents unsettled.

“It has just been very frightening,” said longtime Big Bear resident Nancy Anderson, who is in her 60s. “We feel like we need to stay put and safe.”

A GRUDGE

Dorner’s grudge with law enforcement is believed to have started in sometime in 2008, after he was fired from the department.

“Your lack of ethics and conspiring to wrong a just individual are over. Suppressing the truth will leave (sic) to deadly consequences for you and your family. There will be an element of surprise where you work, live, eat and sleep,” he wrote in the manifesto. “I never had the opportunity to have a family of my own. I’m terminating yours.”

Dorner began working for the LAPD in 2005. Three years later, the department recommended he be sent to a Board of Rights hearing, and if found guilty, be relieved of duty, according to a complaint dated Jan. 24, 2008.

The complaint involved a 2007 confrontation in which Dorner and his partner responded to a report of a man disturbing the peace in San Pedro.

Dorner and his partner requested backup as they used force to arrest the man. Two weeks later, Dorner told department officials that he failed to report that his partner kicked the arrested man in the upper body and face while Dorner tried to place him in handcuffs.

Dorner’s partner denied kicking anyone, and three independent witnesses supported her statement. In the manifesto that Dorner posted online, he described himself as a whistle-blower, but the report questioned Dorner’s claim.

“The delay in reporting the alleged misconduct coupled with the witness’ statements, irreparably destroy Dorner’s credibility, and bring into question his suitability for continued employment as a police officer,” the report read.

The report also stated Dorner was struggling to reintegrate into the department after returning from a year of military service.

“Whether that in some way created the motivation for him to make this complaint is not known, however it does not rationalize it,” the report stated.

Beck described Dorner’s manifesto as “self-serving” and called on the former officer to turn himself in.

“No one else needs to die,” he said.

Register staff writers Claudia Koerner, Alejandra Molina, Thomas Martinez, Alyssa Duranty, Mike Reicher, Tony Saavedra, Landon Hall, Brooke Edwards Staggs and Rebecca Kheel contributed to this report.

Contact the writer: 714-704-3788 or shernandez@ocregister.com