The shootings began shortly before 5:30 pm on Wednesday in Bakersfield, about 90 miles north of Los Angeles.
Authorities are still investigating how the other victims were involved, Youngblood said.
They learned that a husband and hi estranged wife showed up at the trucking business to confront a man at the business. He shot his ex-wife and then turned the gun on a second man, 50-year-old Antonio Valadez, the sheriff's department said.
The gunman, who was not identified, then went to a home nearby and shot and killed two more people.
The victims were shot at and near a trucking company, and then at a residence in Bakersfield.
'He was shooting rounds at the man and chasing him in a circle, ' witness Manny Meza told via the latimes. 'It's not something I thought I'd ever see.
Although he added that "This is the new normal, if you look across the country, these types of shootings".
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Casarez fired at Valadez as he ran away, but then tracked him down in his auto and killed him, the sheriff said.
Investigators said he next stole a vehicle with a woman and child inside, but they were not harmed.
His next stop was at a nearby house, where he killed a man and the victim's adult daughter, who may have tried to protect her father, Youngblood said.
The incident at multiple locations that lasted approximately a half-hour started when the shooter, 54-year-old Javier Casarez, took his ex-wife to T&T Trucking, Inc., on Manwell Boulevard. The mother and child were able to escape unharmed, Youngblood said. USA Today reports that the vehicle's owner called 911 to describe the attacker and the vehicle, and the suspect was soon spotted by a deputy on Edison Highway.
"Obviously, these are not random shootings", said Youngblood, but could not elaborate on the possible motive of the attacker.
Investigators are questioning around 30 witnesses in the case.
He killed himself after he pulled into a business and was confronted by police, who released body-cam footage of the suicide from an officer at the scene.