GERMAN police said they were working on the assumption that the explosions which rocked the Borussia Dortmund football team's bus last night were caused by "serious explosive devices".
They said devices which went off near the bus as the Bundesliga side were leaving their hotel for a home Champions League quarter-final against Monaco "may have been hidden in a hedge near a parking area".
Dortmund defender Marc Bartra suffered injuries to his arm and hand in the incident, thought to have been caused by glass from the nus's shattered windows.
The match was rescheduled for tonight.
Police said there were three explosions near the bus as it left a hotel on the outskirts of the city for the stadium, around six miles away.
Dortmund said Bartra, who is Spanish, had been taken to hospital, but the club's chief executive Hans-Joachim Watzke said the defender's injuries are "nothing life-threatening".
Dortmund goalkeeper Roman Buerki said the team bus had just pulled out of the hotel driveway when an explosion sent glass flying.
The Switzerland international told reporters he was sitting in the last row of the bus, next to Bartra.
Bartra was hit by shards from the broken back window, he added. Players ducked for cover, wondering whether there would be more explosions.
"We're all shocked - nobody thought about a football match in the minutes after that," he said.
Inside the packed stadium, supporters of Monaco chanted "Dortmund, Dortmund" in sympathy for the German side. Dortmund residents used social media to offer accommodation to stranded Monaco supporters.
Dortmund chief executive Watzke said: "The team is totally shocked, that's clear. It's our task now to digest this somehow because it's only 24 hours before we have to play. That's our job."
Stadium spokesman Norbert Dickel informed fans of the postponement, saying "there is no reason for panic here at the stadium".
German justice minister Heiko Maas wrote on Twitter: "Shocking news. Our thoughts are with Borussia Dortmund. You'll never walk alone!"
Germany has seen matches postponed over security concerns before.
In Hannover, in November 2015, Germany's international friendly against the Netherlands was cancelled just before kick-off after police feared an explosive device might be detonated at the stadium.
That came days after devices were detonated outside the Stade de France in Paris as France was playing Germany, part of the co-ordinated attack on the French capital.
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