Dortmund are scheduled to play AS Monaco in the Champions League quarter-final this evening.
But the club announced there was an explosion near the team hotel.
The German club tweeted: "Bomb explosion by team bus at team hotel. Players safe. No danger in or around stadium.
Bombenexplosion am Mannschaftsbus am Mannschaftshotel. Spieler in Sicherheit. Keine Gefahr im und am Stadion. Weitere Infos folgen. #bvbasm
— Borussia Dortmund (@BVB) April 11, 2017
"Please keep calm. Emergency talks now taking place at the stadium."
German newspaper Bild say the explosion shattered the windows of the bus and Spanish centre-back Bartra was taken to hospital after being hurt in the incident.
An update is expected at 7.30pm UK time to determine whether the game will go ahead.
Borussia Dortmund defender Marc Bartra
Dortmund police released a statement which said: "In the run-up to the Champions League match of the BVB against the AS Monaco, there was an explosion near the BVB team team bus shortly after 7 pm.
"According to current knowledge the disks of the bus (whole or partial) were broken and one person was injured.
"It is not yet possible to say exactly what the explosion was or exactly where something exploded."
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