Police said officers have been deployed in the area surrounding the Altmarkt-Galerie shopping center, Russia Today reported.
According to Bild newspaper, a 40-year-old gunman killed a 70-year-old woman on Saturday morning. He then reportedly tried to break into a local radio station while firing a handgun, and later fled to the mall.
The paper said he had hidden in a drugstore, where he took hostages.
Photos from the scene show heavily armed officers in the mall.
MNA/PR