At about 21:00 local time, on a train traveling on the line between Treuchtlingen and Würzburg, a youth, armed with a hatchet and a knife, stabbed random passengers, injuring a family of four Hong Kongers, two critically.

[6][16] Riaz Khan Ahmadzai, born on 6 April 1999 (Pashto: رياض خان احمدزی), also known as Muhammad Riyad,[17] was reported to be a 17-year-old Afghan male who arrived in Germany as an unaccompanied child refugee in 2015.

[18] Authorities later discovered evidence showing that Ahmadzai was in contact with a suspected Islamic State member and had originally been asked to drive a car into a crowd of people.

[29] Amaq News Agency published a two-and-a-half minute video, allegedly of him speaking in Pashto, proclaiming himself a soldier of the Caliphate, threatening further IS attacks in "every village, city and airport" and holding a knife.

The Chief of the German Chancellery, Peter Altmaier, told ZDF television, "The security authorities expect that this video is in all likelihood authentic".

[37] Rolf Tophoven, director of the Crisis Prevention Institute in Essen told Le Monde that the perpetrator was "integrated" and wasn't known to police or intelligence agencies.

[39][40] Hong Kong Chief Executive Leung Chun-ying condemned the attack as he dispatched a team of immigration officers to accompany the victims’ relatives to Germany.

[41][42][43][44] The attack was linked to the European migrant crisis, and was reported to have raised more questions about Angela Merkel's open-door refugee policy.

[46] Former federal minister Renate Künast of the Green Party was ridiculed by police union chief Rainer Wendt as a "parliamentary smart aleck" for asking why the perpetrator was shot dead instead of arrested alive.