"Unfortunately numerous people - a tour group from (the eastern German state of) Saxony - lost their lives in this burning bus," government spokesman Steffen Seibert told a news conference.
A local newspaper, Frankenpost, said that 17 people had been killed, without identifying its source for the information.
Police said on Twitter that "a number of people" had died with 31 people injured, some of them seriously.Police said there had been 48 people on the bus at the time of the crash.