Eight people, including German, Austrian and Swiss citizens, are missing following a landslide that forced the evacuation of a village in the Swiss Alps, police said Thursday.

"In the region of Val Bondasca, eight people who were there at the time of the landslide have not been found," the Graubunden cantonal police said in a statement. 

The Wednesday morning landslide sent mud, rocks and dirt flooding down the Piz Cengalo mountain into the outskirts of the village of Bondo, near the Italian border.

Roughly 100 people were evacuated, with some airlifted out with helicopters.

Police had initially announced that no one was hurt in the landslide.

But on Thursday they acknowledged that rescue workers were flying over the area in search of mountain climbers and hikers who might have been hit by the slide.

Six of the eight people known to have been in the area and who have not yet been located had been reported missing by their relatives, the police said, adding that the search for them had intensified overnight, with a Swiss army helicopter taking part.

"The missing persons are nationals from Germany, Austria and Switzerland," the police said.

"There are often hikers in the affected area," Graubunden police spokesman Markus Walser told the Blick daily, adding that the area did not have mobile phone reception.

"We hope this is the reason we have not been able to reach the people believed to be in the area," he added.

- Buildings destroyed -

Images showed an unstoppable mass of thick mud and sludge moving down the mountainside like lava, ripping apart at least one building in its path and partially engulfing others.

A broad swathe of farmland was covered in a grey, moving mass.

Police said 12 farm buildings, including barns and stables, had been destroyed by the flow of debris, while Graubunden's main southern highway, linking Stampa to Castasegna, was closed to traffic.

Police on Wednesday evacuated Bondo, and had also evacuated two Alpine cabins, pointing to the risk of further landslides.

Residents have not yet been permitted to return home. Authorities said they would reevaluate the situation Thursday afternoon.

Wednesday's landslide was not the first to hit Piz Cengalo,

In 2012, nearly 400 million cubic metres of mud, rocks and gravel -- the equivalent of 4,000 standard-sized houses -- poured down the mountainside, landing in an uninhabited valley.

Following that incident, an automatic debris alarm system was installed. 

That alarm was set off when Wednesday's landslide barrelled down the mountain at 9:30 am (0730 GMT), police said, sparking an immediate deployment of emergency services.

The last deadly landslide to hit Switzerland happened in November 2014, when the earthfall caused a building in Davesco-Soragno in the southern canton of Ticino, killing two people and injuring four others.

One of the worst such accidents in the wealthy Alpine country in recent years happened in 2000, when 12 people perished and four others were declared missing after floods set sediment moving in the canton of Valais.

Source: AFP