Police in the western German town of Sinzig ended a six-hour hostage alert on Friday by storming a Volksbank branch and freeing two people who had been locked in a strongroom — only to discover that the suspected captors had already vanished. The bizarre resolution left investigators with an empty vault, no arrests, and no explanation for how the perpetrators escaped.

The alarm began around 9 a.m. local time when regional police received reports of armed individuals inside the bank, according to a police statement. Authorities said they believed several perpetrators were holding multiple hostages, including the driver of an armored cash-transport vehicle.

Officers surrounded the building, and heavily armed special forces prepared for a prolonged standoff. Shortly before 3 p.m., the tactical team entered the bank. They found two people locked in a safe room, but no one else.

The two captives were physically unharmed, police said. The perpetrators had apparently fled immediately after shutting the two inside the vault, but it remains unclear how they managed to leave the building undetected.

Police have not disclosed whether money or valuables were taken from the bank. The investigation is ongoing.

Sinzig, a town of roughly 17,000 residents in the Rhine valley near Koblenz, was the scene of the unusual incident.