UPDATE: A man known to authorities as an Islamist has been arrested. See more updates below.

A series of explosions set off near the Borussia Dortmund’s team bus last night rocked the vehicle and injured one of the team’s star players, Marc Bartra.

++BREAKING++#Germany

Explosion hits bus carrying pro football team @BVB in #Dortmund prior to int'l match. One person injured: police. https://t.co/F07dWGjuc2 — Daniel H. Heinke (@daniel_heinke) April 11, 2017

The three explosions were caused by an apparent IED remotely detonated with a mobile phone.

While authorities initially tried to downplay any possible terrorist connection, reports early this morning indicate that the case is now being considered a possible act of terrorism after a note found at the scene indicated a possible Islamist motive.

German police say bombs that struck Borussia Dortmund team bus were detonated by MOBILE PHONE in a 'targeted attack' https://t.co/xuBW3WeA21 — Daily Mail Online (@MailOnline) April 11, 2017

UPDATE: police say they found a letter near the scene taking responsibility – but won't reveal other details https://t.co/38gPwUmCFf — Daily Mail Online (@MailOnline) April 11, 2017

Some of the details of that note claiming responsibility are now coming to light.

Deutsche Welle reports:

Three explosions went off near Borussia Dortmund’s team bus as it set off for the Champions League quarterfinal match against AS Monaco on Tuesday, authorities said. According to local media reports, the case has been handed over to federal prosecutors, which usually means an incident is considered terrorism or a similarly serious crime. Further reports indicated that a note found near the explosives began “in the name of Allah, the merciful,” and that investigators were looking into possible Islamist connections. Police spokesman Gunnar Wortmann confirmed there were “three explosions near the [Borussia Dortmund] team bus as they left the hotel to go to the stadium.” Dortmund police said on their Twitter account said they “assume that this was an attack with serious explosives.”

One German media outlet has obtained the text of the note.

.@SZ reports: note claiming responsibility for #Dortmund attack names sports personalities and celebs from "crusade countries" as targets — Kate Brady (@kbrady90) April 12, 2017

An edited Google Translate version of the note reads:

In the name of Allah, the Most Gracious, the Most Merciful, 12 unbelievers will be killed by our Blessed Brethren in Germany… Your Tornadoes [German military aircraft] still fly above the ground of the caliphate to assassinate Muslims. However, we remain steadfast by the grace of Allah. As of now, all the disbelieving actors, singers, sportsmen and all prominent figures in Germany and other Crusader nations are on the death list of the Islamic State. And as long as the following demands are not fulfilled: Removing Tornadoes from Syria. Rammstein Air Base must be closed.

A self-styled “anti-fascist” group also claimed responsibility:

Police investigate 2nd responsibility claim in #Dortmund @BVB attack. Reportedly from anti-fascists bemoaning lack of anti-neo-nazi action https://t.co/j5Ns5uyoig — Kate Brady (@kbrady90) April 12, 2017

Riding the wave of attention? 2nd note in connection with #BVB explosion – Far-left say police don't do enough about neo-Nazis in #Dortmund — Elizabeth Schumacher (@ElizSchumacher) April 12, 2017

The explosions and threats notwithstanding, the two teams have vowed to hold the soccer match tonight.

#BVB CEO Hans-Joachim #Watzke: "I have spoken to the players and told them to show everybody that we don't bow to terror." #bvbasm https://t.co/lXxtJxkOdN — DW Sports (@dw_sports) April 12, 2017

The #BVB players are now out on the training pitch and are preparing for this evening's re-arranged match. Kick-off 18:45 CET #bvbasm https://t.co/yvMVpuevU0 — DW Sports (@dw_sports) April 12, 2017

#BREAKING Football: Champions League security to be reinforced after Dortmund attack – UEFA — AFP news agency (@AFP) April 12, 2017

And despite the rivalry, Borussia Dortmund fans worked to accommodate AS Monaco fans who were stranded after the match was canceled.

Massive respect to fans of #BVB for providing accomodation to fans of #Monaco. True spirit of football! We are all one. #YNWA — KL Kopites (@KL_Kopites) April 12, 2017

We will continue to monitor the situation and any additional reports on the investigation.

UPDATE: Bild reports that an Islamist known to authorities is under arrest for the bombing.

https://twitter.com/BreakingNLive/status/852145517161271297

And a second man is also under arrest. Police gave a briefing within the hour. Here’s a translated version:

#Dortmund: according to BILD, the second suspect is a 28-year-old German from Fröndenberg — I.E.N. (@BreakingIEN) April 12, 2017

Police are saying that they are treating the incident as an act of Islamic terrorism.

Police: "We are treating this incident as a terrorist attack. An Islamic background is possible." #bvbexplosion — DW Sports (@dw_sports) April 12, 2017

And it sounds as if the injuries from these IEDs could have been considerably worse:

Police: "Explosives contained metal shards – we can be happy that nothing worse happened." #bvbexplosion — DW Sports (@dw_sports) April 12, 2017

Police latest on #Dortmund @BVB bus attack: one of explosives contained metal rods, could reach up to 100m, assume terrorist attack — Kate Brady (@kbrady90) April 12, 2017