The ski resort Mammoth Mountain shut down all lift operations on Friday, Feb. 14, after an avalanche slid on Lincoln Mountain, a popular area known for steep tree skiing and chutes, according to the ski resort’s website.

Police ask people to "use extreme caution" and be aware of weather conditions before recreating outside after separate tragedies claim 3 skiers.

A growing number of skiers, weary of high prices and long lift lines at crowded resorts, are turning to the solitude of backcountry slopes. But the avalanche dangers are real, and skiers should go in prepared.

In Oregon's Cascade Mountains, an avalanche killed two backcountry skiers, while another was killed in an avalanche near South Lake Tahoe, authorities said.

Another skier, in an avalanche separate from the one in Oregon, was killed near Powderhouse Peak in California, around 111 miles east of Sacramento, according to the El Dorado County Sheriff's Office. On Monday, the victim was reported overdue to the county's dispatch, police said. The skier was later found dead by friends in an avalanche area.