This is an archived article and the information in the article may be outdated. Please look at the time stamp on the story to see when it was last updated.

BORREGO SPRINGS, Calif. — A man and two teenage boys suffered burns Friday in an explosion during a school field trip to a desert campground in the eastern reaches of San Diego County, authorities reported.

The blast in the 200 block of Palm Canyon Drive in Borrego Springs happened shortly after 9 a.m., apparently when flammable fumes wafted into a campfire, according to Cal Fire.

“Something caused it to flash,” said Nick Schuler, a battalion chief with the state agency. “The report is there was some propane or some alcohol nearby, and when I say alcohol, I don’t mean the drinking kind, but fuel of some type.”

Medics airlifted the 39-year-old man — who suffered second-degree burns over about 30 percent of his body — and the two 14-year-olds to UCSD Medical Center in San Diego. It was unclear how severely injured the boys were, though the trauma apparently was limited to their legs, Schuler said.

The victims were part of larger group from High Tech High School in Point Loma.