Three bombs exploded as the bus ferried the team to the Westfalenstadion for the first leg of their quarter-final against Monaco in the UEFA Champions League.

On 21 April 2017, German police arrested a man on suspicion of planting bombs to drive down the Borussia Dortmund share price and profit by put warrants he bought prior to the attack.

[5] Spanish footballer and Dortmund's team member Marc Bartra was wounded by shards of glass from the shattered bus window; he was taken to a nearby hospital where his right wrist was immediately operated on.

[8] At the time, the bus was on its way to the first leg of Borussia Dortmund's 2016–17 UEFA Champions League quarter-final against Monaco at the Signal Iduna Park; the match was rescheduled for the following day, which they lost 3–2.

[9] The German police and state lawyers treated the bombing as attempted murder and a planned attack on Borussia Dortmund.

The German Federal Prosecutor's Office initially called the attack an act of terrorism with possible Islamist involvement.

The letters said the attack was retaliation for German military intervention against Islamic State (ISIS) in Iraq and Syria, accusing it of being responsible for killing Muslims.

Unlike previous video claims of responsibility, the letters directly addressed the German chancellor and had no religious justifications, ISIS logo, or signature.

Initially there were claims that the Borussia Dortmund supporter's groups were infiltrated by neo-Nazi sympathizers which in the beginning, people believed could have led to the terrorist attacks.

[21] The letter also threatened another attack on protesters who plan to demonstrate against the Alternative for Germany party's conference in Cologne on 22 April.

[28][21] On 21 April 2017, the federal prosecutor announced that it had arrested a 28-year-old German-Russian citizen, identified as Sergej Wenergold, on suspicion of 20-fold attempted murder, bringing about an illegal detonation of explosives, and aggravated battery.

It was revealed that on the day of the attack, he had bought put warrants for €78,000 from an investment bank using the internet connection in his hotel room.

The unusual transaction raised suspicion of money laundering with bank employees, prompting them to alert authorities and pass to them the identity of Wenergold, which led to his arrest.

[30] Marc Bartra, a defender for Borussia Dortmund, testified at the trial of Wenergold and saying that he feared for his life as the bomb blew up and injured him.