Because of an allegedly armed passenger in a coach, the Bavarian police have completely blocked Autobahn 9 between the Hilpoltstein and Greding junctions in both directions.
The ICE route between Munich and Nuremberg, which runs next to the autobahn, is also affected.
Only the two bus drivers were on the bus with the allegedly armed passenger on Tuesday evening, as a spokesman for the Middle Franconia police told the dpa news agency.
All other passengers would be outdoors on the hard shoulder.
As the news portal nordbayern.de reported, there should have been a dispute between several people on the bus around 5 p.m.
A witness claims to have seen that a person was armed.
A police negotiating group is in action, and SEK units are also said to be on site, as is a police helicopter.
According to information from nordbayern.de, the emergency services keep a distance of 500 meters from the bus.
It is an "unclear threat situation".
According to information from the Bild newspaper, the bus comes from abroad.