The three American firefighters who died when their water tanker crashed while battling wildfires in Australia on Thursday were from a California-based crew, according to a statement from California Gov. Gavin Newsom.

His statement did not identify the crew members but called them “heroic.”

“This tragic accident reminds us all of the too-high cost of the scourge of wildfires, as well as the sacrifice of first responders from around the world,” he said. “California and Australia, already united by the deadly threat of wildfires, now grieve this tragic loss together.”

Canada-based Coulson Aviation said one of its large Lockheed air tankers, a C-130 Hercules, was lost after it left Richmond in New South Wales with retardant for a firebombing mission.

“We are deeply saddened to confirm there were three fatalities,” Coulson Aviation said in a statement. “Our thoughts and prayers are with the families of the three crew members on board.”

The tanker was the same one seen at McClellan Air Force Base during an event with Newsom and former California Gov. Arnold Schwarzenegger last year to highlight the state’s new firefighting equipment.

The C-130 had been used as part of a training program in 2019 for future pilots of the Cal Fire program and had also been used to battle wildfires across California, including the Kincade Fire in Sonoma County.

New South Wales Premier Gladys Berejiklian confirmed the three deaths in the Snowy Monaro region, as Australia attempts to deal with an unprecedented fire season that has left a large swath of destruction.

Coulson grounded other firefighting aircraft as a precaution pending investigation, reducing the number of planes available to firefighters in New South Wales and neighboring Victoria state.

AUSTRALIAN WILDFIRE PROMPT $11G FINE FOR TOSSING LIT CIGARETTE FROM VEHICLE

Australian Transport Safety Bureau, the national air crash investigator, and state police will investigate the crash site, which firefighters described as an active fire ground.

“There’s no indication at this stage what’s caused the accident,” Rural Fire Service Commissioner Shane Fitzsimmons said.

CLICK HERE TO GET THE FOX NEWS APP

The Thursday plane crash raises the death toll from to at least 31 since September. The fires have also destroyed more than 2,600 homes and razed more than 25.7 million acres -- an area bigger than Indiana.

Fox News’ Brie Stimson and The Associated Press contributed to this report.