A bus carrying members of the Borussia Dortmund football team was hit by explosions in Dortmund, Germany, on Tuesday evening. Defender Marc Bartra broke a bone in his wrist in the incident that took place after the bus left the hotel where the team was staying for their Champions League quarter-final match against AS Monaco, reported BBC. The match was postponed by a day because of the incident.

Investigators said the three explosions took place in what they believe was an attack targeted at the team. “After the initial investigation, we assume that this was an attack using serious explosives,” unidentified Dortmund police officials told Reuters. Reports suggested that the explosives were placed outside the bus. No other players were hurt in the explosions that shattered the windows of the bus.

The police has yet to figure out the reason behind the attack. The police have also found a letter near the site of the attack. However, the investigators have so far refused to reveal details about its content and authenticity.

The first leg of the quarter final matches is being played at Signal Iduna Park stadium that can hold more than 80,000 people. It is the largest in the country. The police had earlier said that there was no risk to the venue.

In 2015, the Stade de France in Paris was attacked in a series of explosions carried out across the city by the Islamic State group. France were playing Germany in a soccer friendly when the incident took place.