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.

German news agency dpa reported seeing the letter, whichi addressed German Chancellor Angela Merkel directly. "You obviously aren't bothered about your dirty little subjects," the note allegedly read. "Your Tornados continue to fly over the ground of the Caliphate to murder Muslims."

A government spokesman said Merkel was "appalled by the attack," and had offered her solidarity with Borussia Dortmund.

"The letter's authenticity is being verified," prosecutor Sandra Lücke told journalists.

- Dortmund bus attacked - as it happened

- Inside the stadium as the attack took place 

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."

At a press conference, police said they did not want to jump to conclusions by saying the three explosions were a terror attack. "We are assuming that they were a targeted attack against the Dortmund team," said Dortmund city's police chief Gregor Lange. An explosive-like item was found at the team's hotel after the blasts but it did not ignite. 

The police were quick to praise the calm reaction of fans, which "helped us and the club enormously." While still in the stadium, Monaco fans chanted "Dortmund! Dortmund!" in support of their Champions League rival. The German club commended the support on their social media account and helped to direct the Monaco fans toward overnight accommodation.

Under the hashtag #bedsforawayfans, hundreds of French supporters found accomodation for the night with locals. DW's Kate Brady in Dortmund met one fan who put up six Monaco fans.

Marc Bartra injuries

The club said defender Marc Bartra injured his arm and his hand and was taken straight to hospital. BVB chairman Hans-Joachim Watzke said Bartra's injuries were not "life-threatening." Borussia Dortmund's representative at a press conference on Tuesday night confirmed that Bartra was undergoing surgery on his injured wrist and lower arm. 

Dortmund goalkeeper Roman Bürki, who was sitting near Bartra on the team bus, chronicled the incident in an interview with Swiss newspaper "Blick," calling it "a proper explosion."

"We departed the hotel at 19:15 (1715 UTC). The bus turned onto the main street when there was a huge bang - a proper explosion," Bürki said in the interview. "I sat in the last row next to Marc Bartra, who was hit by splinters of broken glass from the back window."

The match was rescheduled to Wednesday.

"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," Watzke was quoted as saying.

dv/es/rt (AP, AFP, Reuters)