Twelve ski instructors were killed after a ski slope near the popular Austrian resort of Kaprun was struck by the country's fourth lethal avalanche in just over a year.
A local police officer said that 11 bodies had been recovered.
Two people had been found alive and were flown out injured, but one died on arrival at Salzburg's regional hospital.
At least one person was still missing and, as daylight failed, hopes faded for the skier's recovery.
The Austrian authorities said nine helicopters and 80 rescuers were scouring the area around the Kitzsteinhorn mountain. Twenty specially trained avalanche rescue dogs which can sniff out people buried in snow were also being used.
The victims were said by police to have been skiing off-piste on the slopes of the mountain when the killer slide roared down in the early afternoon.
Witnesses said the avalanche was about 150 yards wide and it had begun away from the Alpine resort's prepared slopes.
Avalanche warnings have been posted in many parts of the Alps in recent weeks as temperatures have risen. Kaprun had seen rain earlier in the day, then sunshine, a combination which is often the prelude to a snow slide.
Lying 56 km south of Salzburg, Kaprun is among Austria's leading ski resorts, with accommodation for 14,000 visitors. All-year skiing is possible on a nearby glacier.
Last December 11 people were swept to their deaths by two snow slides in Austria. Ten months earlier the country suffered its worst skiing disaster in decades when a series of avalanches claimed the lives of 38 people in the high-Alpine area around Galtur in Tyrol.
Yesterday the bodies of the dead were flown by helicopter to the nearby Niedernsill sports centre, where they were put in the basement awaiting identification.
Avalanche experts warned that the survival chances for anyone caught in the avalanche sink dramatically after 15 minutes.
"More than 90 per cent of victims die through suffocation," said Mr Rudi Mair from the Tirolean avalanche warning centre. "Access to air is quickly lost and only in the case of a quick rescue does one stand any chance."
Experts said they believed that two snowboarders had triggered the avalanche. A group of ski instructors from Denmark, Austria, the Czech Republic and Germany were caught in the mass of snow as it thundered down the mountainside.
One of the injured, a 34-year-old Danish ski instructor who had been working for the skiing season in Austria, died after being transported to Salzburg's regional hospital.
No Irish nationals were believed to be among the dead or injured.