Another cruel mystery in Deutschland

The cultural enrichment of Germans continues:

One person was killed and four wounded in a knife attack in a supermarket in the northern German city of Hamburg on Friday, the city's police said.

More:

German daily Bild published a picture of the attacker in the back of a police car with a white, blood-soaked bag over his head, and reported that he cried "Allahu Akbar" (God is Greatest) in the supermarket.

The German police are quite perplexed:

"We have no clear information as to the motive or the number of wounded," Hamburg police said in a tweet.