BERLIN (AP) — A bus headed from Stockholm to Berlin came off a highway in northeastern Germany on Friday and overturned, injuring 22 people, authorities said.

The accident happened about 6.30 a.m. at Linstow, near Rostock, on the A19 highway. The bus veered into a ditch next to the highway and ended up lying on its side.

FlixBus, the main operator of long-distance buses in Germany, said the bus was heading from Stockholm to Berlin via Copenhagen. Ferries from Scandinavia arrive in Rostock.

Police said there were 61 passengers and two drivers on board from 22 countries. They said 16 people sustained medium to serious injuries and were taken to nearby hospitals, while the remaining passengers were looked over at an aid station in the nearby city of Guestrow and six of them were taken to hospital with light injuries.

It wasn't immediately clear why the bus left the highway. No other vehicles were involved.

Police said the driver was questioned and a breathalyzer test showed an alcohol level of zero. Investigators were analyzing an on-board data recorder to try to understand the accident.