Mountain Tragedy

Three members of the Mammoth Mountain ski patrol were killed yesterday morning after falling into a deep gas vent, a natural hazard on the mountain. They were overcome by noxious gases.  (Brian Vander Brug / LAT)

Mammoth Mountain ski hosts stand along a roped-off area to insure guests do not approach the Christmas Bowl area where three Mammoth Mountain ski patrol members died yesterday. They were overcome by noxious gases following a fall into a deep gas vent.  (Brian Vander Brug / LAT)

Mammoth Mountain CEO Rusty Gregory outlines what happened to three ski patrol members yesterday. They were killed after falling into a deep volcanic vent.  (Brian Vander Brug / LAT)

A skier passes by during a press conference with Mammoth Fire Department Chief Brent Harper this morning. Three members of the Mammoth Mountain ski patrol were killed yesterday morning after falling into a deep volcanic vent.  (Brian Vander Brug / LAT)

Bill Cockroft, Mammoth Mountain senior vice president, secures a fence post in the area where snow collapsed around a deep gas vent in Christmas Bowl. Three Mammoth Mountain ski patrol members were killed yesterday morning following a fall into a deep gas vent.  (Brian Vander Brug / LAT)

This is a sign similar to ones posted near gas vents on Mammoth Mountain. Three Mammoth Mountain ski patrol members died yesterday after they were overcome by noxious gases following a fall into a deep gas vent.  (Brian Vander Brug / LAT)