Rescue crews responding to a wreck on a San Fernando freeway found a driver fatally shot in the head, while another driver was shot and wounded in a separate attack about 30 miles (48 kilometers) away in Long Beach, authorities said.
The incidents were the latest in a string of Southern California freeway shootings stretching back several weeks.
The San Fernando Valley victim is thought to have crashed his car after being shot on the 101 Freeway early Sunday morning, Los Angeles police Officer Norma Eisenman said.
The unidentified man was found early Sunday by rescue crews responding to a report of a rolled-over vehicle on the freeway, Los Angeles Fire Department spokesman Cecil Manresa said.
The victim's white Honda Accord hit a sound wall before flipping across the freeway lanes, he said. Rescue crews had transported the man to a hospital in critical condition, he said.
Authorities did not know what led to the shooting and were trying to establish exactly where it occurred. The car crashed near a freeway onramp, so it is possible the victim was shot on a surface street and then drove onto the highway, Eisenman said.
"There's absolutely no witnesses at this time, no information," she said.
Authorities initially closed off two lanes of the freeway, then the entire eastbound side when it became clear the death was a homicide. The freeway remained closed for nearly six hours.
Meanwhile, about 30 miles (48 kilometers) southwest in Long Beach, police were investigating a second freeway shooting that left a man hospitalized with non-life-threatening injuries.
The shooting victim told officers he was driving north on the 710 Freeway near Del Amo Boulevard Saturday evening when another motorist shot at him, Long Beach police Officer Jackie Bezart said.
The victim was able to drive himself off the freeway and phone for help, she said.
The man characterized the shooting as a road-rage incident, Bezart said.
The incidents come about a month after the shooting in late February of a 46-year-old man who was hospitalized after taking bullets in the torso and right arm while driving on the Foothill Freeway northeast of Los Angeles.
In another incident, a 26-year-old man died after a shooting on the 101 Freeway in the San Fernando Valley on March 1 that followed an argument on Hollywood Boulevard.
A 54-year-old woman was found about two weeks later shot in the head in a car crashed on the San Bernardino Freeway in eastern Los Angles County. She later died at a hospital.
It was not immediately known if arrests had been made in those shootings.