CROCKETT (KRON) — Multiple agencies are now trying to piece together what caused Tuesday’s tank explosion and fire at the Nustar fuel storage facility and whether the company violated any regulations before during or as a result of the incident.

“What investigators are doing as we speak is they’re doing a site survey,” Erika Monterroza said. “They are interviewing any witnesses that were there when the incident occurred, employees, employers, if unions were involved. They’re interviewing union representatives. They’re also doing a very thorough review of all of the safety and training records.”

Monterroza is with Cal/OSHA, the state worker safety agency that is among those investigating the incident. 

It is Cal/OSHA that issued the shutdown order, that means the facility will remain closed until Nustar can prove it can operate safely again.

But state regulators say Nustar has not had problems before.

“At that work site, Cal/OSHA has no incidents of work place safety and health inspections that resulted in violations. “

As the investigation proceeds, Nustar is working to clean up the facility.

In a statement the company says vacuum trucks are removing fire-fighting water and foam which was contained onsite, though there is no mention of whether there is still ethanol in those ponds.

The company goes on to say, “Our engineering teams are on the ground working with inspection companies to assess adjacent tanks and equipment for mechanical integrity… with regard to air quality… we conducted air monitoring in multiple sites for a multitude of potential contaminants… all were below detectable levels.”

Also Thursday, Crockett firefighters had to return to the hillside adjacent to the facility that caught fire Tuesday, when a small spot fire rekindled.

It was quickly put out.