Chevron has responded to Thursday's oil tank explosion in Lost Hills by shutting down oil and gas production equivalent to almost 15,000 barrels per day, or about 9 percent of its total California output.

The explosion, which county firefighters estimate caused $10 million in damage, destroyed a 5,000-barrel oil tank used to separate oil from water and other substances that come up during pumping.

"Chevron's production from the Lost Hills field is shut in and will remain so until (it) can be brought back on line safely," spokeswoman Carla Musser wrote in an email.

"Our primary concern is ensuring the safety of our employees, business partners, public health and the environment."

Local authorities have reported that no one was injured in the blast, which sent the tank's roof flying 150 feet away. They said two nearby tanks were damaged.

Cal-OSHA said it is not investigating the explosion because no workers were hurt. County officials said they are helping coordinate an investigation being led by Chevron.

A representative of the California Energy Commission said it is not investigating. A spokesman for the state's top oil regulatory agency, the Division of Oil, Gas and Geothermal Resources, said an incident report will be filed but that he was unsure whether there would be a "full-fledged" investigation.