L.A. County Fire Department crews responded around 2 p.m. to the quarry in the 7300 block of Pearblossom Highway in Littlerock, just southeast of Palmdale, to reports of a burning vehicle.
County Fire Chief Anthony Marrone said a short time after crews arrived, perhaps around 2:10 p.m., an explosion occurred, killing Andrew Pontious, a 19-year veteran firefighter.
"Pontious was assigned to FS 93 in the City of Palmdale," read a post on X by LACoFD. "He faithfully served our Department along w/ #LACounty residents & communities for over 19 years."
A second firefighter who was near the blast was taken to Antelope Valley Medical Center, but did not suffer any serious injuries and was being released from the hospital, Marrone said.
"I don't know how the fire started and I don't know what exploded,'' Marrone said, noting that a thorough investigation will be conducted.
Marrone called Pontious a "wonderful man," saying he was married and was a father. Eyewitness News learned Pontious leaves behind one child.
"It's just such a tragedy," he said.
By late afternoon, the large front-loader was still burning and sending thick black smoke into the air. Fire crews kept their distance from the equipment, which was in an isolated dirt area did not present any danger of spreading flames to other vehicles.
Crews kept a hose line on the vehicle, and most of the flames appeared to have been doused by early evening.
Los Angeles County Supervisor Kathryn Barger, whose district includes the Littlerock area, issued a statement saying her "heart is heavy'' to learn about the death.
"My deepest condolences to his family and the other firefighters at Station 93,'' she said. "It's a sobering reminder of the dangers our first responders face every day. We owe them our steadfast support as they grapple with this loss. I'm committed to ensuring our fire personnel are connected with needed mental health support as they grieve.''
City News Service, Inc. contributed to this report.