Updated 8:42 p.m.
(AP) — A fire at a fuel storage facility in the San Francisco Bay Area prompted a hazardous materials emergency Tuesday afternoon that led authorities to order about 12,000 people in two communities to stay inside with all windows and doors closed.
Emergency sirens blared and thick plumes of black smoke and flames filled the skyline around the NuStar Energy LP facility in Crockett, about 30 miles northeast of downtown San Francisco.
Video footage of the fire showed flames leading up to an explosion so strong it blew the lid of one of the tanks high into the air.
"This is a very dynamic, rapidly evolving situation," Capt. George Laing of the Contra Costa Fire Department said. "We've got two tanks that are releasing chemicals that are still burning."
The primary concern to the public was unhealthy air quality caused by hazardous particulates spewing from the fire.
The tanks were part of a cluster of fuel storage facilities along an industrial span next to the Carquinez Strait, a major shipping thoroughfare and a key oil hub.
The NuStar facility is also close to Interstate 80, one of the busiest highways in the San Francisco Bay Area, which officials shut down Tuesday afternoon, causing massive backups at the height of evening rush hour. The California Highway Patrol said the closure was expected to last at least until midnight.
Contra Costa Fire Department spokesman Steve Hill said the two burning tanks contained about 250,000 gallons of ethanol and firefighters were trying to keep the blaze from spreading to other tanks storing jet fuel. At an evening news conference Hill corrected an earlier report in which he had said three tanks caught fire.
Ethanol typically produces a blue flame, leading firefighters to assume the fuel in the tanks may be mixed with another fuel.
"What you're seeing behind you is obviously not a blue flame, it's a black flame," Laing told KPIX-TV. "So it could be mixed material, it could be mixed fluids from multiple tanks. 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 the number one thing they are finding out right now."
About 200 firefighters were battling the blaze, Hill said.
Crews were using water to cool tanks adjacent to the ones already burning to prevent the fire's spread, said firefighting expert Marcelo D'Amico of Texas-based Orcus Fire and Risk. At the same time, foam was being sprayed from fire trucks and delivered via a fixed system installed at the facility to help douse the flames, he said.
Ultimately fire officials might decide to switch to a "defensive approach" if it appears the flames won't spread, D'Amico said.
"If they hold the perimeter, they could say, 'hey, these tanks are already on fire, but there's a limited amount of time until the fuel burns itself out,'" he said.
Ethanol fires are not necessarily any more difficult to fight than blazes burning gasoline or diesel, according to D'Amico.
Petroleum experts were on the scene to assist in the firefight, county fire officials said.
A resident of Rodeo, Gabriel Iturbe, sat in bumper-to-bumper traffic as he tried to get home to his teenage son, who was home sick when he called his father to report a loud explosion.
"It literally rocked the house and then soon after, he heard what sounded like a jet plane," Iturbe said, speaking from his cellphone in the car as he looked at "thick, black smoke." He said he was trying to reach his son and take him out to a less smoky location.
In a statement, NuStar Energy said it was cooling nearby tanks to minimize the spread of fire but provided few other details. The company is a fuel storage and pipeline operator based in San Antonio.
The Contra Costa Health Department posted on Twitter that there was a "hazardous materials emergency" in the towns of Crockett, home to about 3,100 people, and Rodeo, population 8,700. The department urged residents to stay inside and close all windows and doors.
"Cover any cracks around doors or windows with tape or damp towels. Stay off the phone unless you need to report a life-threatening emergency at your location," the department said.
Officials said they did not immediately know the cause of the fire and whether there was any connection to a 4.5-magnitude earthquake Monday night centered in the East Bay city of Pleasant Hill, north of Oakland.
That quake caused malfunctions at two nearby oil refineries operated by Shell and Marathon oil, Randy Sawyer, Contra Costa County's chief environmental health and hazardous materials officer, told KQED News. Some equipment at the Shell refinery was temporarily affected by the quake, spokesman Ray Fisher said.
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