GENEVA (AP) — A Dutch tour bus overturned in eastern Switzerland in a serious accident that left several people dead and others injured, police said.

The bus overturned Thursday afternoon between the villages of Susch and Zernez in the Alpine canton of Graubuenden, and rescue teams were responding to the scene, authorities said. The police did not specify the number of dead and injured.

According to Swiss media, 48 people were on the bus. A spokeswoman for ANVR, a Dutch travel industry association, told the Blick newspaper that the passengers were Dutch.

A police spokesman said the coach collided with the crash barrier and then overturned. No other vehicles were believed to be involved.

Oad, a travel agency behind the trip, said in a statement in Dutch that it was “deeply shocked and devastated by the tragic bus accident” and its thoughts were with those involved and their loved ones.

The Dutch Foreign Ministry said it was too early to know the number of victims. Swiss President Guy Parmelin, writing on X, vowed that Swiss authorities would ensure a “comprehensive and thorough investigation” of the case.

Several ambulances and five helicopters were deployed to the location, according to Swiss media.