According to Kern County Sheriff Donny Youngblood, who spoke at a news conference late Wednesday, a husband and wife had visited the shop and got in a confrontation with a man there.
The first of a locations was a trucking business, where the attacker confronted his wife and another man, then shot and killed both.
He did not disclose the identities of the victims, and added the woman whose vehicle was taken, and her child, were unharmed.
He then halted a vehicle with a woman and child inside before stealing the auto.
The attacker then fatally shot two more men at another location, before hijacking a auto with a woman and a child on board.
A gunman in the United States killed five people, including his wife, before turning the gun on himself as police closed in.
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About 30 people saw the shootings and were being interviewed by deputies, Mr Youngblood said.
As the deputy confronted him, the gunman turned his gun on himself to take his own life. The body camera video from the officer who confronted the shooter also needs to be examined.
Police say that none of the shootings were random.
"This is highly unusual to have six people shot and dead in one incident", Youngblood said. "Then I saw a guy with a gun, shooting", said the witness, who declined to be identified.
Deputy Donny Youngblood says the investigation spans multiple crime scenes and deputies will work through the night to find out what went wrong.
Referring to recent shootings across the country, Youngblood decried Wednesday's events as the "new normal".
Bakersfield is a community of 375,000 people about 115 miles (185 km) northeast of Los Angeles.