An explosion and fire ripped through storage tanks at NuStar refinery storage facility Tuesday, sending flames and smoke billowing into the skies, CBS San Francisco reported. The incident began unfolding at around 2 p.m. PT in the massive petroleum tank storage farm nestled in the hills of Crockett, according to the Vallejo Firefighters Association.

The fire ignited the vegetation on a hillside bordering the storage tanks. Approximately 200 firefighters and support personnel were dispatched, according to CBS San Francisco.

The smoke and fire kicked up again shortly before 5 p.m. and reignited once more shortly before 7 p.m., sending towering flames up alongside a third tank as crews frantically tried to keep the fire from spreading. It was contained shortly before 9 p.m., and the shelter in place was lifted by 12:30 a.m.

NuStar Fire is now contained. County Environmental Health HazMat teams are working to assess the current health threat in Crockett, Rodeo, and Hercules. — Con Fire PIO (@ContraCostaFire) October 16, 2019

In a statement, NuStar told CBS News it was "working with first responders to extinguish a fire at its Selby Terminal in Crockett, CA." The statement added that there are two impacted tanks, which were holding very low volumes of ethanol -– "less than 1% of tank capacity," according to the statement.

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"All personnel are safe and accounted for," the statement added. "NuStar immediately enacted its emergency response procedures. Adjacent tanks are being cooled to minimize the risk of the fire spreading. We have contacted all regulatory agencies."

Contra Costa County Fire Protection District Captain George Laing told CBS San Francisco that the thick black smoke indicated other substances were burning. "It could be mixed material, it could be mixed fluids from multiple tanks," Laing said. "There could be manifolds, valves and pipes down there. At this point, it's still actively involved in fire so I'm sure that's number one thing they are finding out right now."

Witnesses reported explosions shaking the area. One woman said she was loading her truck at the refinery when the explosion rocked the facility.

A fire rages after a refinery explosion in California CBS San Francisco

"I had just pulled off the rack and gotten my paperwork," the woman, identified as Michelle, told CBS San Francisco. "I had my head down doing paperwork and I felt the ground rumble. I knew there was an earthquake yesterday. So I didn't panic."

"But I looked up and saw a bunch of people running," she added. "I looked and I saw the fire and the smoke. I immediately started my truck and headed up the hill. I got to the top of the Cummings Skyway, and I could see the tops of two tanks completely engulfed in flames."

She added the tanks stored renewable diesel fuel, not gasoline.