BERLIN (AP) — At least five people were killed Wednesday when a bus headed from Berlin to Switzerland came off a highway in eastern Germany and ended up on its side, authorities said.

The accident happened on the A9 highway near Leipzig at about 9:45 a.m. and the road was closed in both directions.

It wasn’t immediately clear why the bus, which was operated by Flixbus and was en route to Zurich after setting off from Berlin at 8 a.m., came off the road. Rescue helicopters and ambulances were at the scene.

Police spokesman Olaf Hoppe told n-tv television that there were “numerous injured and at least five dead.”

Flixbus said there were 53 passengers and two drivers on board. The company said it was working closely with local authorities and rescue services and would do everything to clear up the cause of the accident quickly.

The double-decker bus was later turned upright to continue the recovery effort, German news agency dpa reported.

The A9 is a major north-south route that links Berlin with Munich. The accident happened on a straight stretch of the road just north of a highway interchange at Schkeuditz, next to the Leipzig/Halle airport.