LITTLEROCK, Calif.—A Los Angeles County firefighter was killed Friday when part of a burning front-loader exploded at a Littlerock quarry.

The Los Angeles County Fire Department did not immediately provide details of the blast, which occurred in the 7300 block of Pearblossom Highway in the community southeast of Palmdale.

Crews are believed to have responded to the quarry around 2 p.m. on a report of a burning vehicle, which turned out to be the front-loader. What happened next was unclear, but reports from the scene suggested part of the vehicle or one of its massive tires exploded, killing the firefighter and possibly injuring another.

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.

What appeared to be a flag-draped body was visible on a large pile of dirt nearby.

KCAL9 reported from the scene that an ambulance had taken at least one other person to a hospital, but there was no immediate confirmation of any other injuries.

County Fire Chief Anthony Marrone and firefighters union Local 1014 President Dave Gillotte were expected to hold an early evening news conference outside Antelope Valley Medical Center to discuss the firefighter’s death.