May 18, 2012 -- 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 today on "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, 43, 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.
"I've never seen anything like this," her doctor, Dr. Andrea Dunkelman, said today on "GMA." "She has third-degree burns, which means that it's been burned all the way through her skin to her underlying tissue, her fat. We treated her by placing skin grafts from her thigh to that area."
Lynn's husband, Rob, suffered burns on his hands in the incident while trying to come to his wife's aid.
"We're exhausted but we're overwhelmed with love and support," Rob Hiner said. "We're just grateful. We're grateful that things weren't worse and God just continues to provide for us in this situation."
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.
"It'll burn right through flesh, bone and skin. I've never heard of anything like this before," Dr. Michio Kaku, author of "Physics of the Future," an examination of science in the coming century, said.
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.
San Diego State University geologist Pat Abbott says this was not Mother Nature's fault.
"I know the orange is not part of the rock," Abbott said. "It's not natural. It's human made."