Mammoth Mountain officials said the slide occurred during avalanche mitigation work following a significant Sierra Nevada snowstorm, during which about six feet of snow fell in 36 hours.

Two ski patrol staff at Mammoth Mountain were caught in an avalanche while doing mitigation work after an atmospheric river dropped about six feet of snow in 36 hours, Mammoth Mountain officials said.

Two people were trapped, one seriously injured in an avalanche at Mammoth Mountain Friday morning during mitigation work following the powerful snowstorm.