CHAMONIX, France—Eight climbers were missing and presumed dead Sunday after an avalanche swamped a commonly used hiking trail near Mont Blanc, western Europe’s highest peak.

The avalanche, triggered when a chunk of ice as wide as two football fields broke off a mountain face, appeared to be the deadliest this year in the French, Swiss or Italian Alps, and the worst in the French Alps in more than a decade, officials said.

“There’s no chance of finding anyone alive,” French Interior Minister Michele Alliot-Marie said while visiting the region. Five Austrians and three Swiss were missing. Seven other people were hospitalized with injuries.

The avalanche began about 3 a.m. after a massive block of ice known as a serac cracked off a side of the Mont Blanc du Tacul, one of the peaks in the Mont Blanc range, at an altitude of some 11,800 feet, the Haute-Savoie regional government office said in a statement.

Authorities deployed a vast search mission, involving four helicopters, dozens of rescue workers, doctors, Alpine guides and sniffer dogs, French officials and the government statement said.

“It’s an area known for avalanches — it (the ice) regularly breaks off here,” Marika Zimmermann, an Alpine climber, said on France-2 television. “They were in the trail, but problem was that the avalanche swept away the trail.”

The regional government at first said 10 climbers were believed missing, but that figure was lowered to eight after two Italians thought to be among them were found already back in Italy.

Seven people were hospitalized — not eight as originally indicated — and of those, only three were staying overnight. Most suffered broken bones or sprains, and a guide who was injured was treated for a broken vertebra but has no risk of paralysis, rescue team leader Jean-Yves Moracchini said.

“The guide shouted, ’Run fast! Run fast!’ It didn’t make any noise. It really was impressive,” said survivor Nicolas Duquesne, a 30-year-old from southern Nice, France, from his hospital bed where he was being treated for a broken ankle and some bruising. “We had just enough time to move away to the right before getting hit ... We were really lucky.”

Regis Lavergne, an Alpine police official, told France’s TF1 television that rescue teams believed nothing more could be done because the missing climbers were caught under the block of ice.

“From the moment we could locate them with radar echo and surface analyses, it was already five hours after the avalanche — so there’s no more hope,” he said. “They skidded between 1,000 and 1,500 meters (yards).”

Moracchini said all rescuers had turned up were two bags, a shoe, and an alerting device carried by climbers in case of avalanches. He said the block of ice was more than 218 yards wide.

French officials said falling seracs aren’t rare, but are typically difficult to predict because they are generally caused by the pressure of the buildup of ice on the mountain, not daily weather variations.

Still, the search was suspended because of the risk that the warm weather could melt other ice blocks and provoke another snow slide, local police and government officials said.

Mont Blanc du Tacul is on one of the routes that climbers often use to reach the top of Mont Blanc, which is western Europe’s tallest mountain at 15,780 feet.

Avalanches intermittently hit the celebrated Mont Blanc range, where dozens of climbers die every year. Causes may include accidents, heart and respiratory problems, and freezing—as well as snow slides.