The gunman is understood to have taken his own life and that of his wife in the incident, which appears to have begun over an altercation at a local trucking business.
There was no immediate word on what sparked the shootings that took place at a home and at the business in Bakersfield, which lies 90 miles north of Los Angeles.
“Obviously, these are not random shootings,” Kern County Sheriff Donny Youngblood told KERO-TV.
Six people died in a short amount of time, he added.
The man first arrived at the trucking business with his wife shortly before 5.30pm local time, where he confronted another man.
“The suspect, the husband, shot the person at the trucking company and then turned and shot his wife,” then chased and shot another man who showed up, Mr Youngblood said.
The gunman then went to a home where he shot two people, the sheriff said.
He then car-jacked a woman who was driving with her child. The woman and child escaped and the man drove off before a sheriff’s deputy saw him, Mr Youngblood said.
When the deputy confronted him at gunpoint, the man shot himself in the chest, the sheriff said.
His identity was not immediately released.
Except for the gunman’s wife, there was no immediate word on how the victims might have been related.
Approximately 30 witnesses are understood to have seen the shootings and are being interviewed by deputies, Mr Youngblood said.
The AP contributed to this report