Three explosions have hit a bus carrying the Borussia Dortmund football team to a home Champions League match, BBC reported.
Player Marc Bartra was injured and has been taken to hospital but is not seriously hurt, reports say.
The team tweeted (in German) that the other players were safe and there was no danger in or around the stadium.
The game has been postponed until Wednesday. The AFP news agency reported that the bus's windows were broken in the blasts.
North-Rhine Westphalia police said they were at the scene.
Borussia Dortmund were scheduled to play a quarter-final match against Monaco.
It will now be played on Wednesday at 18:45 local time (16:45 GMT).
Dortmund are currently fourth in the German Bundesliga table.