In Big Bear Lake

A San Bernardino County officer checks a house on Sylvan Glen Avenue in Big Bear Lake for shooting suspect Christopher Jordan Dorner. The ex-police officer's truck was found burning in the mountain area. (Wally Skalij, Los Angeles Times / February 7, 2013)

As the scope of Christopher Jordan Dorner's ambitions sank in Thursday, thousands of police hunted him and waited, on edge, as he seemed determined to hunt them.

At departments across the Southland, bulletproof vests and riot gear were strapped on, shotguns readied. Motorcycle cops rode inside the protective metal of squad cars. The joking morning chatter had been replaced by grim quiet.

Their adversary was a linebacker-sized ex-cop with a multitude of firearms, military training and a seemingly bottomless grudge born when the LAPD fired him in 2009. Before dawn Thursday, authorities said, Dorner had already struck twice — grazing an LAPD officer's head with a bullet in Corona, and firing on two Riverside officers, killing one and wounding another.

It was the third homicide police have attributed to Dorner, 33, a former U.S. Navy reservist who is also accused of killing the daughter of a retired LAPD captain and her fiance in Irvine.

Police across California and Nevada launched an unprecedented manhunt involving hundreds of officers from dozens of agencies.

In a Facebook manifesto police say Dorner wrote, he ranted against LAPD personnel who he said fired him unfairly. He threatened revenge, "unconventional and asymmetrical warfare" against police and their families, saying he would stalk them "where you work, live, eat, and sleep."

Authorities took him at his word.

"Of course he knows what he's doing — we trained him," Los Angeles Police Chief Charlie Beck said. "It is extremely worrisome and scary, especially to the police officers involved."

Police are guarding at least 40 people mentioned in his screed. Security was tight at LAPD headquarters, with officers stationed around the perimeter. Beck himself was being escorted by extra officers.

Police are struggling to discern a pattern in Dorner's recent movements. A burly man matching his description tried to steal a boat about 10:30 p.m. Wednesday at the Southwestern Yacht Club in Point Loma, tying up the elderly owner, threatening him with a gun and saying he wanted to flee to Mexico. The thief gave up when a rope got tangled in the propeller. Dorner's old LAPD badge was found a short distance from the boat.

Three hours later, 100 miles away near an offramp of Interstate 15 in Corona, a resident recognized Dorner's Nissan Titan pickup truck and flagged down LAPD officers who were en route to guarding one of his would-be targets, police said.

After a brief chase, Dorner opened fire with a rifle, grazing one officer in the head with a bullet that came within inches of killing him. Police returned fire, but the gunman escaped.

Minutes later in nearby Riverside, two city police officers were attacked as they sat in their marked patrol car at a red light at the corner of Magnolia and Arlington avenues, police said. Bullets penetrated the windshield and struck both officers in the chest, killing a 34-year-old veteran and wounding the 27-year-old officer he was training. That officer is expected to survive.

It was a "cowardly ambush," said Riverside Police Chief Sergio Diaz.Police across the Inland Empire converged on Riverside to help with the manhunt, and officers held rifles and shotguns as they stood guard outside the police station.

"My opinion of the suspect is unprintable," Diaz said. "The manifesto I think speaks for itself as evidence enough of a depraved and abandoned mind and heart."

The names of the officers who were shot have not been released. There is fear Dorner may come after them again, or their families. At schools near the shootings, some wary parents kept their children home. Other schools were closed.

As news of the shootings crackled across police radios before dawn, the hunt for Dorner's Nissan Titan pickup truck intensified.

About 5:20 a.m. in Torrance, two women were delivering the Los Angeles Times from their blue pickup when LAPD officers spotted the truck.

The police apparently mistook the truck for Dorner's and riddled it with bullets. The women, a mother and daughter team, were rushed to a hospital.

The mother, who is in her 70s, was shot in the shoulder. She was listed in stable condition. Her daughter was injured by shattered glass.

Hours later, the truck — perforated by numerous bullet holes — sat on the street near the home of an LAPD official who was cited in the manifesto and was under LAPD protection. Beck said the department was investigating the circumstances of the shooting.

"Tragically, we believe this is a case of mistaken identity," he said.

Near the shooting of the newspaper delivery women, local resident Ron Way, a Vietnam veteran, said he feared that Dorner's military training would ramp up the carnage. "He's on some Rambo rampage," Way said. "I believe he is damaged."

About 25 minutes after that shooting, Torrance police opened fire after spotting another truck similar to Dorner's at Flagler Lane and Beryl Street. No one was reported hurt.

"If I had a [Nissan] Titan, I would park it today," said Walter Howe, 60, at a Torrance Starbucks.

Vera Smirnoff, who was walking outside a 99 Cent Only store at Anza Avenue and 190th Street in Torrance, said the fugitive shooter made her uneasy. So did police. "Be leery of calling them, because they are nervous," Smirnoff said. "I hope they are not trigger happy."

At a news conference Thursday morning, Beck called the situation "extremely worrisome and scary, especially to the police officers involved." Asked what he would say to Dorner, Beck replied: "I would tell him to turn himself in. This has gone far enough. No one else needs to die."

By the afternoon, the focus of the investigation had moved east to Big Bear. There, a TV helicopter showed images of a burning truck on the side of a snowy mountain. Authorities determined it was Dorner's Nissan Titan and were following foot tracks into the mountains.

Big Bear resident Jim Lyon, a member of the local volunteer search and rescue team, decided to stay home: "I'm just sitting here with my 9mm on my lap."

andrew.blankstein@latimes.com

phil.willon@latimes.com

christopher.goffard@latimes.com

Times staff writers Kate Mather, Matt Stevens, Garrett Therolf, Robert J. Lopez, Angel Jennings, Nicole Santa Cruz, Lauren Williams, Kate Linthicum, Joel Rubin, Jack Leonard, Jill Cowan, Hailey Branson-Potts, Tony Perry in San Diego, Ruben Vives in Riverside and Joseph Serna in Big Bear contributed to this report.