Local, state and federal authorities are involved in a massive manhunt for Dorner, who is believed to have threatened "unconventional and asymmetrical warfare" against police in an online manifesto. Dorner is also wanted in connection with a double homicide Sunday in Irvine, where the daughter of a retired LAPD captain and her fiance were killed.

Beck urged anyone who sees Dorner to immediately call 911 and not approach him.

When asked what he might say to Dorner, Beck replied: "I would tell him to turn himself in. This has gone far enough. No one else needs to die."

"Of course he knows what he's doing — we trained him," Beck told reporters Thursday morning. "It is extremely worrisome and scary, especially to the police officers involved."

Beck said suspect Christoper Jordan Dorner, 33, had multiple weapons at his disposal, including an assault rifle, and called the ex-LAPD officer and former Navy reserve lieutenant "armed and extremely dangerous."

As the search continued Thursday for a former police officer suspected of a double homicide and shooting three police officers, one fatally, Los Angeles police Chief Charlie Beck called the situation "extremely worrisome and scary."

The search intensified early Thursday — and warnings spread across California and Nevada — after three police officers were shot in Riverside County and Dorner was identified as a possible suspect.

The first shooting occurred about 1:30 a.m. Thursday in Corona, where two Los Angeles Police Department officers were providing protection for someone mentioned in Dorner's supposed manifesto, officials said. One officer suffered a graze wound to the head during a shootout and Dorner fled the scene, police said.

A short time later, two Riverside officers were shot at the corner of Magnolia Avenue and Arlington Avenue in Riverside. Toussaint said the officers were sitting at a red light when they were ambushed. One was killed, the other was undergoing surgery Thursday morning.

“Our officers were stopped at an intersection at a red light when they were ambushed," he said. "Because of the close proximity to the timeline, we believe there is a strong likelihood that former LAPD Officer Christopher Dorner was involved in our incident.”

As authorities swarmed the area, two officer-involved shootings occurred in Torrance after police encountered suspicious vehicles.

The first Torrance incident occurred about 5:20 a.m. in the 19500 block of Redbeam Avenue, Lt. Devin Chase said. That incident involved Los Angeles police detectives from the Hollywood division, sources said.

Beck said police were in the area on protection detail for one of the officials mentioned in the manifesto when authorities received information a vehicle matching the description of Dorner's was seen in the area. Police then observed a vehicle with its lights turned off and approached it, at which point the shooting occurred.

Beck said the two people inside the vehicle were struck and taken to an area hospital. One person suffered a minor wound, Beck said, the other — struck twice — was listed in stable condition.

Sources said the women were delivering newspapers.

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

The second incident, which involved Torrance police officers, occurred at Flagler Lane and Beryl Street about 5:45 a.m., Chase said. No injuries were reported in that incident.

Chase said both incidents involved vehicles matching the description of the one Dorner is believed to be driving.

"Now it appears neither of them are directly related," Chase said. "In both of them, officers believed they were at the time."

Authorities said they believe Dorner attempted to steal a boat from an elderly man about 10:30 p.m. Wednesday at the Point Loma Yacht Club in San Diego, hours before the shootings in Riverside County.

INTERACTIVE MAP: Searching for suspected shooter

The boat owner reported being accosted by a burly man who tied him up, threatened him with a gun and said he wanted the boat to flee to Mexico.

But while they were trying to get underway, a rope became entangled in the propeller and the boat was inoperable, authorities said.

The suspect fled the scene and the boat owner was unharmed.

About 2 a.m., a citizen reported finding property belonging to Dorner on a street near Lindbergh Field, not far from the scene of the attempted boat theft. The property included a briefcase and Dorner's LAPD badge.

PHOTOS: Manhunt for ex-LAPD officer

In the online manifesto, Dorner specifically named the father of Monica Quan, the Cal State Fullerton assistant basketball coach who was found dead Sunday in Irvine along with her fiance, Keith Lawrence.

Randy Quan, a retired LAPD captain, was involved in the review process that ultimately led to Dorner’s dismissal. A former U.S. Navy reservist, Dorner was fired in 2009 for allegedly making false statements about his training officer. In the manifesto, he complained that Randy Quan and others did not fairly represent him at the review hearing.

“The violence of action will be high .... I will bring unconventional and asymmetrical warfare to those in LAPD uniform whether on or off duty," Dorner wrote.

ALSO:

Search for ex-cop in shootings extended statewide, into Nevada

Women delivering newspapers in Torrance shot in manhunt for ex-cop

Ex-LAPD cop wrote he was heavily armed, planned widespread violence

— Andrew Blankstein, Kate Mather, Robert J. Lopez, Phil Willon and Tony Perry