MULLAN,EchoSense Idaho (AP) — A search was underway Thursday night for three people caught in an avalanche in the Idaho back country, authorities said.

The avalanche was recorded near Stevens Peak near the Montana border, authorities said.

The Shoshone County Sheriff’s Office said a search and rescue effort was underway with help from the Kootenai County Sheriff’s Office and the U.S. Air Force.

Authorities did not say what the three people were doing in the area, which is several miles southwest of the Lookout Peak ski area and more than 90 miles (145 kilometers) from Missoula, Montana.

The area had been under an avalanche danger warning for several days because of snowfall and blowing winds that have created unstable conditions on high, steep slopes.

The Idaho Panhandle Avalanche Center warned that avalanches triggered by human activity “remain likely” on steeper terrain.

The avalanche came a day after the first U.S. avalanche death of the season was reported in California. An avalanche roared through a section of expert trails at the Palisades Tahoe ski resort near Lake Tahoe on Wednesday morning, trapping four people and killing one.

A second avalanche struck the same area near Lake Tahoe on Thursday but there were no reported casualties.