A huge mass of rock and ice from a glacier thundered down a Swiss mountainside on Wednesday, sending plumes of dust skyward and coating with mud nearly all of an Alpine village that authorities had evacuated earlier this month as a precaution.

Video on social media and Swiss TV showed the mudslide near Blatten, in the southern Lötschental valley, with homes and buildings partially submerged under a mass of brownish sludge.

Regional police said a 64-year-old man was reported missing, and search and rescue operations involving a drone with the thermal camera were underway.

“What I can tell you at the moment is that about 90% of the village is covered or destroyed, so it’s a major catastrophe that has happened here in Blatten,” Stephane Ganzer, the head of security in the southern Valais region, told local TV channel Canal9.

The regional government said in a statement that a large chunk of the Birch Glacier above the village had broken off, causing the landslide, which also buried the nearby Lonza River bed, raising the possibility of dammed water flows.

“There’s a risk that the situation could get worse,” Ganzer said, alluding to the blocked river.

He said the army had been mobilized after earlier indications that the movement of the glacier was accelerating.

At a news conference, Swiss Environment Minister Albert Rösti lamented “an extraordinary event” and said the government would take steps to help villagers who lost their homes.

In recent days, the authorities had ordered the evacuation of about 300 people, as well as all livestock, from the village amid fears that the 52 million cubic feet glacier was at risk of collapse.

Local authorities were deploying by helicopter and across the area to assess the damage, Jonas Jeitziner, a spokesman for the Lötschental crisis center, told The Associated Press by phone.

Swiss glaciologists have repeatedly expressed concerns about a thaw in recent years, attributed in large part to global warming, that has accelerated the retreat of glaciers in Switzerland.

The landlocked Alpine country has the most glaciers of any country in Europe, and saw 4% of its total glacier volume disappear in 2023.

That was the second-biggest decline in a single year after a 6% drop in 2022.

In 2023, residents of the village of Brienz, in eastern Switzerland, were evacuated before a huge mass of rock slid down a mountainside, stopping just short of the community.

Brienz was evacuated again last year because of the threat of a further rockslide.