Vandals caused thousands of pounds worth of damage when they decided to brick up the doorway of a German subway train, in a case which has left police and the train company baffled.
The newly-built wall, consisting of breeze blocks and expanding foam, was discovered by the driver of the S11 train after leaving the above-ground depot in the Barmbeck area of Hamburg on Tuesday.
It called at around a dozen stations across the city before a member of public reported something was wrong.
Passengers on board the S-Bahn had to be evacuated, and the train was taken in for repairs believed to total more than £7,000 (some 10,000 euros).
Police have now launched an investigation and are scouring CCTV footage to try to track down those responsible for blocking-off the entrance.
A spokesman for the Bundespolizei (federal police) told German news outlet The Local that they had no clue as to why the vandals had decided to strike - particularly in such an unusual fashion.
Police have also warned against copycat crimes, saying the offence was punishable by up tp five years in jail or a fine.