TRUCKEE, Calif. – A California State Fire Marshal’s Office report concludes that antifreeze in Henness Flats’ sprinker system likely contributed to the Aug. 18 explosion that killed a woman and injured four others.

The report, from consultant Stephen Hart, states it is his opinion the fire and explosion were most likely caused when Wuliber Martinez, 30, apparently started a fire in a frying pan while cooking onions and tried to extinguish the flames when the fire sprinkler directly above activated, “discharging a solution of glycerine-based antifreeze which was ignited by the flames coming from the burning onions in the frying pan and resulting in the explosion of the glycerine solution.”

The report attributes the fatal burn injuries to his wife, Isela Minutti, 27, the severe injuries to Martinez, and injuries to their children; ages 12, 7, and 10-days, to that explosion.

Hart describes a similar incident at a resort in New Jersey in 2001, in which witnesses at the restaurant said they heard a “pop” sound and a fire sprinker activate, followed by a fireball.

He wrote that investigators reported, “When the system activated, the mixture of Propylene Glycol and water sprayed under pressure on to the ceiling heater located in front of the sidewall sprinker. At that time the vapors from the sprayed liquid ignited and flash fire occurred.”

In the 2001 incident report, 18 injuries were listed, including two people treated at a burn center.

Bob Bena, Truckee Fire Protection District’s assistant chief and fire marshal, said Hart’s report isn’t a sure thing, however.

“It’s still under investigation and still pending lab testing – ultimately it has to be duplicated, and that is supposed to be done by the (property owner’s) insurance company’s investigation team,” Bena said. “As we speak nobody knows for sure that’s what happened.”

The Truckee Fire Protection District also has hired a fire protection engineer to oversee the re-activation of the fire sprinkers in the apartment building, Bena said, to ensure that improper mixing of water and antifreeze isn’t an issue in the future.

Phone calls to Jeffrey Passadore, president of Cambridge Realty, which manages the property, were not immediately returned.