(NEW YORK) -- A California mother is recovering from second- and third-degree burns after colored rocks her family collected from a southern California beach unexpectedly caught fire while in her shorts pocket.
"We were talking about who was going to pick up the babysitter," Lyn Hiner said Friday on ABC's Good Morning America. "And all of a sudden something hot on my leg just sort of started to bother me so I started thinking it was a bug bite, so I started slapping it and the next thing I know my pants were on fire."
The harmless-looking, green- and orange-colored rocks, which Hiner's daughters found Saturday on San Onofre State Beach in southern California, are now the subject of an intense scientific investigation.
Hiner had put the rocks in her pocket after they left the beach. As she and her husband, Rob Hiner, were preparing to go out later that evening, the rocks suddenly erupted in her pants.
Rob Hiner, who appeared on GMA alongside his wife at the Santa Ana, Calif., burn center where she is being treated, said the couple had no idea what was happening.
"It was just this bright intense flame," he said. "We didn't know what it was. Our first response was just to try to pat it out."
"But, in trying to pat it out, it wasn't going out so the next thing was just to try and drop and roll and eventually we just tried to tear her shorts off and got them off of her," he said.
Fire authorities responded to smoke alarms in the couple's home that were set off because the flames in Lyn Hiner's pockets were so intense.
"There were actual flames coming off of her cargo shorts," Orange County Fire Authority Capt. Marc Stone told ABC News. "The husband was outside with a garden hose, actually trying to cool her leg down."
The couple were eventually taken to the Grossman Burn Center, where Lyn Hiner continues to recover from the severe burns on her hands and leg.
Lynn's husband, Rob, suffered burns on his hands in the incident while trying to come to his wife's aid.
Scientists investigating the mysterious explosion say there were seven rocks in total that the Hiner children took from the beach. Field tests found traces of phosphorus -- the flammable orange chemical used in matches -- on the rocks.
The beach where the rocks were collected is near Camp Pendleton Marine base. But Marine officials say there's no evidence any military materials were involved.
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