Colorado’s top oil and gas regulators on Monday hit a subsidiary of Occidental Petroleum Corp. with an $18.25 million fine — by far the largest ever levied by the state against an energy company — for its role in a house explosion in Firestone that killed two men three years ago this week.

A federal probe determined that the April 17, 2017, blast, which killed Mark Martinez and Joey Irwin as the men were replacing a hot water heater in the basement, was caused by natural gas leaking into the home from a severed underground pipe.

Erin Martinez, Mark Martinez’s wife and Irwin’s sister, spoke in front of the nine-member commission of the Colorado Oil and Gas Conservation Commission via video conference Monday afternoon.

“We are coming up on the three-year anniversary of the explosion and to the ones who love Mark and Joey it feels like time has stood still,” said Martinez, who also was badly injured. “Nothing has gotten easier and if anything time has only intensified our pain. It worsens with each passing day, and it is hard to breathe. It is difficult to wrap your mind around the fact that a fine is the only recourse when such devastation and tragedy was the result.”

The fine was levied on Kerr McGee, a subsidiary of Occidental Petroleum Corp. Kerr McGee was a subsidiary of Anadarko Petroleum, which oversaw the pipeline at the time of the explosion and was purchased last year by Occidental.

Mark Mathews, an attorney representing Occidental, addressed the commission Monday: “Kerr McGee knows that nothing it says or does here today can bring back what was lost in this accident but it is our hope the extensive safety efforts it has undertaken over the past three years and the penalty now being paid will prevent a tragedy like this from happening again.”

The COGCC announced the proposed fine last month to punish Kerr McGee for the destruction of the Martinez home. The fine approved Monday is more than 10 times larger than the previous top penalty assessed by the agency against an oil and gas company — a $1.6 million Noble Energy fine in 2018.

COGCC Director Jeff Robbins last month explained that “the aggravating factor of death” boosted the fine amount. Erin Martinez chastised the industry in her statement to the commission.

“As an industry, it is critical that you are held responsible to properly maintain all and any equipment left in the ground,” she said. “The bottom line, had you done your job correctly, my husband, my children’s father, and my brother would be alive today. Had the flowline been properly abandoned from the beginning, then nothing that transpired after would have led to the explosion.”

Anadarko reached an undisclosed settlement agreement in 2018 with the families of victims and survivors.

The National Transportation Safety Board concluded last fall that the likely cause was a natural gas leak through a pipeline that had been cut during construction of the home two years earlier.

Fire investigators found a plastic pipe running from an Anadarko well near the house that had been cut when a tank battery was moved before the Oak Meadows subdivision was built five years ago. That pipeline leaked the gas from a point 6 feet from the southeast corner of the home.