BERLIN (REUTERS) - Shots were fired outside a building in central Cologne on Friday (Jan 4) and one suspect has been detained, Bild newspaper reported on its website.

Police cannot rule out there might be additional gunmen, the tabloid added.

Police advised on Twitter to stay away from the area near the central train station and landmark Cologne Cathedral as they prepared to search the building with special units.

A police spokesman later said the incident may be related to biker gangs. He added that police detained one armed person after shots were fired close to the city's main train station, which serves as a major transport hub in the region.

(This story is developing)