(NBC News) -- A series of violent carjackings early Tuesday left four people dead, including the suspected gunman, in multiple locations across Southern California, police said.
Investigators responded to at least five different crime scenes during the gunman's violent rampage, authorities said at a joint news briefing by Tustin and Santa Ana police and the Orange County Sheriff's Department.
The ordeal began when the suspect, identified as a male in his 20s, shot and killed a woman while trying to steal her car in an upscale section of Ladera Ranch early Tuesday, said Jim Amormino, an Orange County sheriff's spokesman. A bystander also was reportedly struck by shots fired in the course of the carjacking.
The suspect's relationship to the dead woman wasn't immediately clear. Authorities said her body was found with multiple gunshot wounds about 4:45 a.m. (7:45 a.m. ET).
The suspect fled in an SUV toward Tustin, Calif., about 20 miles away, Amormino said.
Police then received a call about a second carjacking involving a man with a gun. The victim of the second carjacking was shot and killed in cold blood on California 55.
Investigators update the deadly carjackings in Southern California.
"He confronted our victim, who was in his BMW, and ordered him out of the vehicle," Santa Ana police Cpl. Anthony Bertagna. "He walks him to the side of the curb and executes our victim."
Police received a third call after a man was seen with a gun in Tustin. Police arrived to find another attempted carjacking and two people shot. One victim was pronounced dead at the scene, and another was transported to a hospital in critical condition, according to Tustin police.
During the rampage, the gunman fired random rounds at passing motorists from a parked vehicle alongside the freeways or after getting out of his vehicle, Tustin police Lt. Paul Graven said. He hit at least three other vehicles and injured one of the drivers, and "we're still investigating how many more victims we might have," Graven said.
Police found the suspect and followed him to the nearby city of Orange. When police tried to stop the vehicle, the suspect shot and killed himself, according to Tustin police. A shotgun was recovered next to him, but authorities said it wasn't clear whether other weapons used.
"There are no other shooters, and there is no threat to the community," Amormino said.