Police and emergency services were deployed to the HypoVereinsbank branch in western Regensburg around 2.50pm on Thursday, following reports of an armed robbery.
The area surrounding the bank was quickly cordoned off and secured, with the Special Task Force (SEK) called in to manage the situation.
According to the Upper Palatinate police, the suspect remained inside the bank early on in the operation. At least one person was seriously injured in the course of the incident, reportedly as a result of a knife attack.
This individual managed to make eye contact with emergency workers outside the building before being transported by ambulance to hospital, where they are said to be in a critical condition.
Authorities believe that several other people are still inside the bank, though it is thought they are not currently being held by the suspect. Police have described the incident as an "ongoing threat situation" and have urged the public to avoid the area.
A police helicopter was seen circling over the city as the operation continued. At this stage, the motive behind the attack remains unclear, and no demands have yet been made by the suspect, according to a police spokesperson.
