CROCKETT, Calif. — The Latest on a fire at a Northern California fuel storage facility (all times local):

7:50 a.m.

Officials are trying to determine if a 4.5 magnitude earthquake triggered an explosion at a fuel storage facility in the San Francisco Bay Area that started a fire and trapped thousands in their homes for hours because of potentially unhealthy air.

The earthquake struck about 15 miles (24 kilometers) southeast from the NuStar Energy fuel storage facility in the Bay Area community of Crockett 15 hours before the fire started Tuesday.

Randy Sawyer, Contra Costa County's chief environmental health and hazardous materials officer, tells KQED News that quake caused malfunctions at two nearby oil refineries operated by Shell and Marathon oil.

County health officials late Tuesday lifted a shelter in place order affecting about 12,000 people. But at least four schools in the area closed on Wednesday as a precaution.

Contra Costa County health department spokesman Karl Fischer didn't immediately return a phone message seeking comment.

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12 a.m.

Authorities are looking into the cause of a fire at a Northern California fuel storage facility that trapped thousands of people in their homes to avoid potentially dangerous air.

It took seven hours to contain a fire that erupted Tuesday afternoon at the NuStar Energy tank farm about 30 miles (50 kilometers) northeast of San Francisco.

The fire followed a 4.5-magnitude earthquake that hit the Bay Area Monday night but fire officials said they haven't determined whether that might have caused any problems at the tank farm.

The fire spewed an enormous black cloud that could be seen for miles and concern that it might contain hazardous particles prompted officials to warn about 12,000 people to stay indoors with their doors and windows sealed.

The warnings were lifted Tuesday night after the fire was contained.

The refinery, meanwhile, is shut down.