SEATTLE — State regulators say a judge erred when he overturned $2.39 million in penalties against Tesoro following the 2010 deadly explosion at its Anacortes refinery.

The Washington Department of Labor and Industries on Thursday asked the state Board of Industrial Insurance Appeals to review the case and affirm the penalties.

In June, the judge hearing the case, Mark Jaffe, vacated 45 alleged violations against Texas-based Tesoro, now known as Andeavor. He said the department failed to show that Tesoro committed any of the alleged violations.

Five men and two women died as a result of the April 2, 2010, blast about 70 miles (112 kilometers) north of Seattle. State regulators called it one of the worst industrial disasters and levied the agency’s largest ever workplace-safety fine.

Regulators said its six-month investigation determined the incident was preventable. Investigators found that a device called a heat exchanger blew apart along cracks in welded areas, the agency said. It said the company did not properly inspect or test equipment at the refinery.

Tesoro appealed the findings to a state insurance board in 2010. Tesoro had disputed the state’s characterization of its safety procedures and inspections, and contends the conclusions of the state’s investigation were mistaken.

Jaffe said in his June 8 ruling that after hearing testimony, reviewing the record and exhibits, he did not find that the department, which has the burden of proof, showed that Tesoro is responsible based on the rules cited in the citation.

The state’s petition filed Thursday contends that from early discovery to rulings on evidence at hearings to his proposed decision and order, the judge didn’t allow the department to present its case to the board. It says evidence supports the department’s citations.

“The Department stands by its citations. Given a proper opportunity, the Department would prove the facts supporting them,” the 220-page petition noted.

“Tesoro hires many workers and serves a role in Washington’s economy. But that does not mean it can have a culture of systemic safety apathy,” lawyers for the state agency argued.

A spokeswoman with Andeavor said in an email Friday that “as a matter of policy, we do not provide comment on legal matters.”

In statements to media outlets in June, Tesoro called the accident a tragedy and supported the judge’s decision to dismiss the claims in their entirety. The company also said that focusing on personal and process safety at the core of what it does at the refinery.

The industrial appeals judge issued a proposed decision and order, but the state Board of Industrial Insurance Appeals reviews that decision and issues a final order.

The board is an independent state agency with three board members appointed by the governor.