The bus came off the A9 motorway and overturned in the morning between Wiedemar and the Schkeuditzer Kreuz motorway junction, police said.
Emergency services attended to the injured at the scene and the motorway was closed in both directions, German authorities said.
The bus belonged to German travel company Flixbus and was on its way from Berlin to Zurich, Flixbus said in a statement.
There were 53 passengers and two drivers on board, the budget operator said.
“The exact circumstances of the accident are not yet known,” Flixbus said.
“We are of course working closely with the local authorities and the emergency services on site and will do everything in our power to clarify the cause of the accident quickly and completely,” it said.
The two drivers both survived, Flixbus added.
Photos showed the bus on its side, having apparently ploughed into trees on the side of the road. Emergency services attended to the injured at the scene and the motorway was closed in both directions, German authorities said. There were no indications that any other vehicles were involved in the crash, according to the police.
German Transport Minister Volker Wissing said he was “shocked” by the accident. “Our thoughts are with the families of the victims and, of course, with all those affected, and we wish the injured a speedy recovery,” he told Welt TV.
Another Flixbus vehicle crashed on the same stretch of motorway in May 2019.
In that accident involving a bus travelling from Berlin to Munich, one person was killed and more than 60 injured, seven of them seriously.
