"I heard loud gunshots... I saw a man with a firearm shooting through a window and filmed it," he said.
Lara Bauch, a 23-year-old student who lives nearby, told the DPA news agency that "there were about four bursts of gunfire - several shots were fired in each burst - with gaps lasting roughly 20 seconds to a minute".
She said that from her window she could see a person frantically running from the ground floor to the first floor. "The man was wearing dark clothing and moving fast," she added.