New Delhi, Feb. 18 -- Rescue crews on skis and snowcats battled blizzard conditions in an effort to reach six backcountry skiers still alive but trapped Tuesday after an avalanche high in the rugged Northern California mountains that left 10 other skiers missing as the danger of more slides remained high.

The search and rescue crews were dispatched to Frog Lake in the Castle Peak area, northwest of Lake Tahoe, after someone called 911 at about 11:30 a.m. to report an avalanche with people buried as a powerful winter storm moved through the state.

Hours later, Ashley Quadros, a spokesperson with the Nevada County Sheriff's Office, said six skiers had been located and were asked to shelter in place "as best they can" until they can be rea...