One man has been killed and three others wounded by a knife-wielding man near Munich, with police investigating a possible Islamist connection.

The man attacked four commuters shortly before 05:00 (03:00 GMT) on Tuesday at Grafing station. One of the victims died of his wounds in hospital.

A 27-year-old German man was eventually overpowered by police and arrested.

Some witnesses said he shouted "Allahu akbar" ("God is great" in Arabic) but the motive for the attack is unclear.

An Upper Bavaria police spokesperson said that a "political motive" had certainly not been ruled out.

Police spokesman Karl-Heinz Segerer told German television that the man "expressed political motivations" during the attack.

They gave no details, saying it is a matter for the investigation.

He identified the suspect as a 27-year-old German national who does not live in Bavaria.

Footage from the scene showed bloody footprints on a train and the station platform in Grafing, a Bavarian town 40km (25 miles) east of Munich.

The police spokesman said one of the victims had been stabbed on the train and others at the station or outside the building.

The mayor of Grafing, Angelika Obermayr, expressed shock at the attack.

"The idea that people get on an S-Bahn train on a beautiful morning or do their paper round and then become victims of a maniac is terrible," she was quoted as saying.

One of the platforms at Grafing station has been cordoned off and commuter trains have been hit by delays.