Premise: BERLIN — German police say they're investigating the explosion of an "apparent pyrotechnical device" in a subway station in the northern port city of Hamburg. Hamburg police said on Twitter there was a "small detonation" on the platform of the Veddel subway station early Sunday evening. They say a pane of glass was damaged, but no injuries were reported. Police say they have information about a suspect and the investigation is continuing.
Hypothesis: The explosion was noticed by many early Sunday.