German police say a man attacked and slightly injured four people with an axe on a long-distance train in Bavaria on Thursday before he was detained by police.
Local police in Straubing said the attack happened on an ICE express train headed to the Austrian capital of Vienna while it was between Straubing and Plattling in southern Germany.
Police said around 500 people were on board when the attack happened.
About 150 police officers, firefighters and emergency personnel were deployed to the scene, police added. The railway line was closed down.
Police did not immediately provide further details on the identity of the attacker or his motive.
The injured were taken to nearby hospitals.
Germany has seen several violent, radical Islamic terror attacks in public spaces in recent months.
In February, an Islamic terrorist plowed into a demonstration in Munich, killing two and injuring more than 20. In December, a terrorist killed six and injured more than 200 when he drove a car through a Christmas market in Magdeburg.