Police are searching an employment building the German city ofCologne, after an armed woman was reported to be inside the agency.
on Thursday, police reportedly cordoned off the building in the Sulz area of Cologne, Germany's fourth largest city, and told the staff to stay in their offices.
There are reports that as many as five people may have been arrested.
The spokesman for police special forces in Cologne said that they had just detained a suspect on another matter at the employment agency when witnesses said they had seen an armed woman walking around in the building.
Bild newspaper reported the special forces operation while local Express newspaper earlier reported that an apparently armed man had been seen in the building.
This comes as Germany is on tenterhooks as a spate of attacks has gripped the European country since July 18.
Last week, a 27-year-old Syrian refugee detonated his explosives in the city of Ansbach in Bavaria, killing himself and injuring 15 people.
On July 19, a teenager, identified as an Afghan asylum seeker who wielded an axe and a knife, wounded four passengers on a regional train, before injuring a passerby. The asylum seeker, whom the officials said could be a Pakistani national, was killed by the police.
The deadliest attack of all came on July 22 when a teenager opened fire at people shopping at a mall in the city of Munich, killing nine and injuring more than 30 others. That was followed by another machete attack in the southwestern city of Reutlingen that left a woman dead and two other people injured.