Kathmandu, Nepal (CNN) -- At least 11 climbers were killed in an avalanche Sunday morning on Manaslu, the world's eighth-highest peak, a pilot who took part in the rescue effort said.
Steve Bruce Bokan of Fishtail Air said that those coordinating the rescue report as many as 38 people missing.
A French mountaineering official put the number lower at 15, but said it had been difficult to get exact figures from authorities in Nepal.
Four French citizens are among the dead, with another three missing, said Christian Trommsdorff, vice president of the National Syndicate of High Mountain Guides in Chamonix, France.
He said that rescuers in helicopters focused on evacuating the injured. They also found the bodies of the four Frenchmen.
One of the survivors -- according to the editor-in-chief for EpicTV.com, a film company that make features on skiing, climbing and other adventure sports -- is Glen Plake, who with two other ski mountaineers had planned to descend from the summit on skis without the aid of oxygen.
Trey Cook said he spoke to Plake by satellite phone and the skier said: "It was a major, major accident. There are up to 14 people missing. There were 25 tents at Camp 3 and all of them were destroyed; 12 tents at Camp 2 were banged up and moved around."
Plake lost a few front teeth and had an eye injury after being swept 300 meters (985 feet) down the mountain, Cook told CNN. Plake was still in his sleeping bag, in his tent and still had on his headlamp he was using to read his Bible verses, Cook said.
After the avalanche, Plake went looking for the rest of the people in camp, all of whom were supposed to be wearing avalanche transceivers -- electronic devices that can signal other similar receivers -- as he was.
Two of his colleagues were missing, including the man with whom he shared a tent, Plake told Cook.
The avalanche, which took place Sunday at about 5 a.m. local time, was likely caused by a huge piece of ice that fell from a glacier above the camp, Trommsdorff said.
Cook said he thought it was a piece of ice the size of six or seven football fields.
Most of the mountaineers had set up tents at 6,600 meters (21,650 feet), said Yograj Kadel of Simrik Air, which was also involved in the rescue. The other mountaineers were apparently 500 meters (1,640 feet) below the camp that was destroyed, according to the EpicTV.com report.
The mountain is 8,163 meters (26,780 feet) high.
Kenton Cool, a mountain climber from England who reached the summit of Manaslu in 2010, told CNN the weather during the post-monsoon season can be quite unsettled. His friends on the mountain told him that in the past 10 days or so there had been "quite high levels of snow on the mountain," he said.
Teams normally wait for new snow to settle before leaving camp.
Officials said bad weather led them to postpone further search efforts until Monday.
Cool, who said Manaslu had a "fearsome reputation," predicted that searchers will have a hard time locating some of the people still on the mountain. The area where the avalanche happened is the site of some large crevasses.
"It will be hard to know exactly where everyone was," he said. "It will be hard to find the bodies, let alone retrieve them."
According to Nepal tourism officials, 231 foreign mountaineers from 25 teams were attempting to climb the mountain in the current autumn season that ends in November. They said that a Spaniard, a German and a Nepalese sherpa had been killed.