An ICE train collided with a granite block in Munich.
According to the federal police, unknown persons had placed it on the tracks near the Langwied stop.
None of the approximately 180 passengers was injured in the collision, investigators said on Tuesday.
They are now investigating a dangerous intervention in rail traffic.
The federal police are looking for witnesses to get information about the perpetrators.
The train was damaged in the collision on Monday afternoon and was no longer operational.
The granite block shattered into four pieces.
The extent of the damage was initially unknown.
The railway line from Pasing to Lochhausen was closed in both directions for around three hours.
The passengers from the damaged train were taken to Pasing.
Long-distance traffic between Augsburg and Munich was severely disrupted.