Four people were reported dead and two wounded in multiple shootings, and police say one of the dead is believed to be the man who shot the others, the Orange County (Calif.) Register reported.
He is believed to have shot himself after police stopped his car on the 55 Freeway in the city of Orange, officials said.
The first shooting was reported about 5:20 a.m. in Ladera Ranch, where a woman was found dead inside a home after a 911 call from inside the home, Orange County Sheriff's Department spokesman Jim Amormino said.
The shooter fled in a sports utility vehicle and then allegedly carjacked three vehicles in Tustin, police said.
Tustin Police Lt. Paul Garavan said the suspect attempted to carjack multiple vehicles in Tustin, with each of the shootings occurring several minutes apart.
In the first carjacking, a bystander was shot but not seriously injured.
The driver of the second carjacked vehicle was shot and killed, police said.
The gunman then hijacked a third vehicle, police said, shooting two people. One of them died, and the other was taken to a nearby hospital.
Police found the suspect, described as a man in his 20s, driving on the 55 Freeway. He shot himself before police said they could make contact with him.
Residents in the area of the incidents described it as upscale, and quiet, the Los Angeles Times said.
"Nothing ever happens here," David Cabada, 26, said as he walked his dog past yellow crime-scene tape after the violence. "The worst that ever happens is somebody gets a traffic ticket."
Homemaker Lisa Eminger said she awoke Tuesday morning to the sound of police helicopters, adding, "This is kind of surreal."