CROCKETT (CBS SF) — Federal agents joined the investigation Wednesday in a search for the cause of a massive explosion and fireball that erupted at an East Bay storage tank farm.

Contra Costa County Fire Protection District spokesman Steve Hill said a search warrant for records was served Wednesday morning at NuStar’s Bay Area offices.

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“At 11:30 this morning we served a search warrant on NuStar,” Hill told reporters. “You should not form any opinion about that because this is a common practice in many, many fire investigation.”

Hill added that NuStar officials were cooperating with the investigation.

Meanwhile, assessment teams surveyed the melted remains of two large storage tanks and the pipelines and determined that was damage to the tank farm’s venting system.

Hill told reporters the tanks were just at 1 percent capacity, containing a combined 250,000 gallons of ethanol, when the explosion and fireball erupted Tuesday afternoon.

“I think we dodged some bullets here in last 24 hours,” he said. “The tanks were mostly empty. That’s a two-edged sword. The tanks were empty so they made more oxygen in them…The point is even at 1 percent capacity those tanks had a lot of ethanol in them.”

Hill said the other tanks on the massive storage farm nestled in the hills above Crockett contained mostly ethanol with one containing jet fuel.

“The good news is it would appear that the work we did to keep them cool that we talked about yesterday afternoon into the evening apparently did its job,” he said. “We haven’t found any structural integrity problems on those tanks and we are not longer concerned about those tanks.”

Early Wednesday evening, Contra Costa Fire officials said there is no threat that another fire will re-ignite at the facility.

Fire teams were pulling out and would turn over the cleanup to NuStar no later than 7 p.m., according to Hill.

By early evening on Wednesday, Contra Costa Fire officials said that the venting of the tanks adjacent to the Tuesday explosion was nearly completed.

The containment ponds where the explosion and fire happened still need drained. Foam blankets remain on top of the mixture of water and ethanol. NuStar would be responsible for evacuating the containment ponds and cleaning up the foam blankets themselves.

Power is back on at the facility, allowing authorities to review cameras to help in the investigation.

Contra Costa Fire said officials could not access documents needed because there has been no power at the Crockett tank farm.

“NuStar and all of their employees and leadership have been nothing but cooperative with the investigation and the operational aspects of mitigating this incident,” said Contra Costa Fire PIO Steve Hill. “You should not infer anything about that either.”

Contra Costa Fire, Cal-OSHA and the Federal Bureau of Alcohol Tobacco and Firearms are teaming up for the investigation

“We expect that this will be a complex investigation with multiple moving parts and multiple agencies.”

Investigators are probing whether Monday’s 4.5 magnitude earthquake about 20 miles away near Pleasant Hill had anything to do with the explosion and subsequent inferno.

The quake, which was felt across the Bay Area, is blamed for causing flaring at two refineries in neighboring Martinez when some equipment shut down after the quake.

“The cause [of the NuStar fire] remains under investigation,” said Hill, who told reporters Wednesday morning it was too early to determine if the Monday night’s quake played a role. “We have a robust investigation going on.”

NuStar has not responded to our requests for comment about the search warrant. Residents in the area want an explanation of what happened quickly.

Todd Coakly wonders, “How did it happen? How does something like that happen, I don’t understand it.”

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Michael Kellogg, who lives just down the street from the facility, said he feels safe and is not worried about the air quality Wednesday evening. He’s lived in the area for the last five years says he’s never had a reason to question safety practices at NuStar.

“As far as I know, they’ve been a good neighbor to me,” said Kellogg.

A team of CalOsha investigators have also arrived at the scene.

With the billowing flames finally abated late Tuesday night, the foam-covered fire scene had a chance to cool off overnight, allowing crews to get close enough to begin accessing the damage.

“The fires that burned yesterday afternoon and well into the evening are both out,” Hill said. “We are continuing to work to make sure we don’t have a re-occurrence of those fires.”

Concerns overnight about the structural integrity of a third tank, charred by the massive flames, lessened when an early morning inspection by the assessment teams only uncovered superficial damage.

“The (assessment) teams got in at first light,” Hill said.

Also still on scene early Wednesday were six firefighting units — two from an industry co-op group formed by the neighboring East Bay refineries and four from local fire departments. They were keeping a watchful eye for any sign of a flare-up.

“The assessment teams were looking for a solution to mitigating the vapor emissions that are coming out of (the containment areas),” Hill said when asked by the lingering concerns early Wednesday.

A shelter-in-place order was lifted for local residents late Tuesday, but the nearby John Swett Unified School District still cancelled Wednesday’s classes as a precaution.

“There is no ongoing public health threat,” Hill said.

Traffic was also flowing on nearby Interstate Highway 80 which was closed by the billowing smoke clouds from the fire until late Tuesday night, triggering an evening commute nightmare.

Hill said both the Cummings Skyway and San Pablo Ave. would re-open to traffic on Wednesday morning.

NuStar said in a preliminary statement that all personnel were safe and accounted for, but Hill said a Chevron firefighter suffered minor injuries overnight.

Crocket Fire Chief Dean Colombo said the NuStar facility had been inspected a few months prior to Tuesday’s fire. But the facility does not have its own fire brigade or fire equipment, Colombo said. It does have fixed equipment to cool down tanks on the exterior in the event of a fire.

Approximately 200 firefighters and support personnel battled the tank fire and also a brushfire that ignited on a nearby hillside.

Witnesses reported explosions shaking the area on Tuesday. Video showed large flames and black smoke coming from the location where two of the storage tanks collapsed.

Photojournalist Alex Montano Reports From Scene Of Massive NuStar Refinery Fire

A woman was loading her tanker truck at the refinery, when the explosion rocked the facility.

“I was loading my truck at that facility when it exploded,” said the woman, identified as Michelle. “I had just pulled off the rack and gotten my paperwork.  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. 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.”


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Andria Borba and Andrea Nakano contributed to this report.