SEATTLE (AP) -- Nearly a dozen people trekking to the summit of Mount Rainier were overtaken by an avalanche, but all except one were pulled from the snow by guides, officials said.

A helicopter Saturday scoured the slope of Mount Rainier, some 60 miles east of Seattle, for the climber and a skier reported in the area who may also have been missing, said Mount Rainier National Park spokeswoman Patti Wold.

But bad weather forced officials to call off the search in the afternoon. Continuing avalanche dangers prevented a ground search. Officials said it might not be safe enough to search again by air or land until Monday.

Several climbing teams were ascending toward the summit of Rainier when the slab avalanche occurred at 4:45 a.m. Saturday at the 12,500-foot level as a large plate of snow broke away from the mountain, Wold said.

The avalanche ran about 1,200 feet down the Ingraham Direct Route and overtook 11 of the climbers, she said.

Ten of the trekkers were pulled from the snow by mountaineering guides but the other person couldn't be located, she said.

A helicopter from the U.S. Army Reserve out of Fort Lewis airlifted two injured climbers from the upper mountain Saturday afternoon. Wold said they were flown to an area hospital and were in stable condition with lacerations and other injuries. There were no reports of any other significant injuries.

Officials said 11th person may have been climbing alone.

"The missing climber did not register for his climb, so we are focusing our efforts on identifying him. Until we do, we are unable to notify his family of the situation," mountaineering ranger Stefan Lofgren said.

According to Colorado Avalanche Information Center, there have been 34 avalanche fatalities nationwide in the 2009-2010 season.

About 5 percent of the more than 10,000 who climbed the 14,411-foot Mount Rainier last year used the Ingraham Direct, according to a park report.