- Three members of a ski patrol were killed when two plunged into a volcanic fissure

MAMMOTH LAKES, Calif. - Three members of a ski patrol were killed when two plunged into a volcanic fissure at the Mammoth Mountain resort and the third fell trying to rescue them, a resort official said.

Four other would-be rescuers were hospitalized for exposure to carbon dioxide and were doing well late Thursday, said Rusty Gregory, chief executive officer of Mammoth Mountain Ski Area.

The Mono County coroner has not determined whether the ski patrol members died from the 21-foot fall or from inhaling toxic fumes.

The victims were part of a four-man team inspecting the mountain after heavy snowstorms and fencing off the rock's gap, Gregory said. The snow collapsed under two patrollers and they fell into the fissure on the 11,053-foot peak in the Eastern Sierra.

"It's likely the heat from the gas vent eroded the snow and didn't support the weight of the patrollers working on the fence," he said.

The other two patrollers saw their colleagues fall and came to help, but one of them also fell in, Gregory said.

The fourth person used a rope to lower himself into the hole and was overcome by gas, but three other responders pulled him out, he said. That patroller survived.

The three who died had multiple years of experience, the most senior with more than 20 years, and they were working carefully because of the heavy snow, Gregory said.

"It's not like they were out there cowboying," he said.

The resort and local officials did not release names of the victims.

One of the dead was identified as Walter Rosenthal, a researcher at the University of California, Santa Barbara, said UCSB spokesman Paul Desruisseaux.

Rosenthal, who was in his 40s, worked at the Sierra Nevada Aquatic Laboratory in Mammoth Lakes. He was an expert in snow hydrology and was identified as the snow and avalanche analyst for Mammoth Mountain.

Mammoth Lakes Mayor Rick Wood said a police detective indicated a significant amount of gas was in the area. Carbon dioxide emissions from the ground have previously been linked to die-offs of trees in the region and have forced campground closures.

The mountain, about a six-hour drive north of Los Angeles, is popular with skiers. The peak towers over a dramatic landscape in a volcanically active region, but that region has been quiet for six years, said Dave Hill, a scientist with the
U.S. Geological Survey
. He said the accident was not related to volcanic activity.

"It's just guys doing a job and it's just an accident," said Shon Eastridge, a gas station clerk. "They were just trying to protect other people's lives and they lose their own."