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A spokeswoman for Germany's federal state prosecutor in Karlsruhe, Frauke Koehler, said: "Two suspects from the Islamist spectrum have become the focus of our investigation. Both of their apartments were searched, and one of the two has been detained."

The blast radius of the attack was about 100m and prosecutors said it was lucky the casualties were not worse. Ms Koehler said a piece of shrapnel had embedded itself in the headrest of one of the seats on the team bus.

Scary stuff.

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German police have detained a suspect with "Islamist links".

Prosecutors also said one of the three explosives used in Tuesday evening's attack contained metal strips.

Two letters claiming responsibility for the attack were being investigated, they said.

Prosecutors are treating the blasts as a terror attack but say the precise motive is unclear at present.

Chancellor Angela Merkel called the bombing a "revolting act".

"The chancellor was, like the people of Dortmund and millions of people everywhere, appalled by the attack on the BVB team bus," her spokesman, Steffen Seibert, said.

It's no surprise that Marc Bartra will not be involved this afternoon, but Dortmund have confirmed that he will watch the game on TV.

Fans hold signs saying "peace" in German and French - both teams have arrived at the Westfalenstadion without incident, with thousands of fans in attendance too. 

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After explosions led to the postponement of the match last night, fans of the German club helped travelling Monaco supporters by giving them somewhere to sleep.

WATCH MORE: How Borussia Dortmund showed their class

It seems to have led to a very friendly - if understandably tense - atmosphere in Dortmund. 

There are four changes for Dortmund from the team thrashed by Bayern Munich at the weekend.

Marc Bartra - obviously - is one man missing as Shinji Kagawa, Sven Bender, Lukasz Piszczek and Julian Weigl all start.

Monaco also make four changes from the win over Angers as Andrea Raggi, Thomas Lemar, Joao Moutinho and the exciting Kylian Mbappe all come in.

As you can see, Marc Bartra is on the mend.

He had surgery on a broken wrist overnight and wishes everyone well for today's game. 

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Police are preparing for a "large deployment" at tonight's rescheduled game, and security at Wednesday's other Champions League ties - Atletico Madrid v Leicester City and Bayern Munich v Real Madrid - is being stepped up.

"Measures are being reviewed and stepped up wherever and whenever it is needed," Uefa competitions director Giorgio Marchetti told BBC Radio 4's Today programme.

"The security risk is the top priority element which is included in the preparation of matches."  

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When Borussia Dortmund left their team hotel to travel the few miles to the magnificent Westfalenstadion 23 hours or so ago, the most pressing concern occupying most of the players' minds would have been how to shut out a Monaco front line who have scored 128 goals this season. 

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Moments later, three explosions rocked them as windows were smashed and defender Marc Bartra was left with a broken wrist.

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We don't yet know exactly what happened, why, or who was responsible for the bombing incident on Tuesday evening.

But what we do know is that today, the show goes on.

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"We do not just play for us today. We play for everyone - no matter whether Borussia, Bayer or Schalke supporters," said Dortmund chief exec Hans-Joachim Watzke this morning.

"And of course we play for Marc Bartra, who wants to see his team win."    

It promises to be an intense, emotional game in Dortmund.