A Deutsche Bahn ICE train opened its door in a tunnel while traveling at high speed near Karlstadt, prompting a police investigation and drone searches for passengers after reports of a door opening in mid-journey.

ICE 528, destined for Frankfurt, halted in a tunnel near Nantenbach in Unterfranken following emergency brake deployment, with 238 passengers aboard.

Another ICE near the Hessian‑Bavarian border stopped in a tunnel after an emergency brake was triggered by an open exterior door.

Reports indicate the incident occurred on September 1, with official timing and location later clarified, drawing on a dpa source.

Bundespolizei is leading the investigation; no suspect has been identified and a technical fault is considered unlikely.

A damaged emergency release was observed, though it remains unclear whether the damage was intentional or accidental.

The investigation continues with checks for the responsible person and review of surveillance; the line was cleared around 2:30 a.m. and Deutsche Bahn has not commented further pending results.

Authorities frame the event as a serious safety incident requiring verification of door integrity and passenger safety, with efforts to understand how the door opened at speed.

The incident occurred on Tuesday evening, with the cause of the door opening still unknown at the time of reporting.

A 32-second video clip accompanies the incident report, which bears a timestamp around 13:30, outlining timeline and facts of the high-speed event.

Advocacy groups urge clearer video documentation in long-distance trains to clarify incidents, while proposing limited retention and restricted release to authorities rather than live monitoring.

investigators have yet to determine who pressed the button; about 120 passengers were identified, and the sequence of events, including whether the lever was pressed, remains unclear.