GENEVA (AP) — Two trains collided in a tunnel on a mountain railway in Switzerland on Friday, slightly injuring a few people, the railway operator said.

A car shuttle train transporting about 15 vehicles hit the side of a local passenger train with about 30 people on board that was traveling in the opposite direction, Matterhorn Gotthard Bahn spokesman Jan Baerwalde told broadcaster SRF.

The cause of the crash near Oberwald, in Valais canton (state) in southern Switzerland, wasn't immediately clear.

The line between Realp and Ulrichen, part of a scenic Alpine route that connects the ski resort of Zermatt with central and eastern Swizerland, was closed following the collision.