Multiple people were killed and several more injured in a knife attack on Friday at a festival in the city of Solingen in western Germany, according to German police. Düsseldorf police spokesperson Anja Kynast told CBS News that at least three people were killed and four others wounded in the attack. Solingen is located roughly 18 miles from Düsseldorf.

Witnesses alerted police shortly after 9.30 p.m. local time to an unknown perpetrator having wounded several people with a knife on a central square, the Fronhof. Police said that the perpetrator was on the run, and that they so far had only very thin information on the assailant.

They said they believe the stabbings were carried out by a lone attacker.

One of the festival organizers, Philipp Müller, appeared on stage and asked festivalgoers to “go calmly; please keep your eyes open, because unfortunately the perpetrator hasn’t been caught.” He said many people had been wounded by “a knifeman.”

In a social media post, Solingen Mayor Tim Kurzbach wrote that the city was “in shock, fright and great sadness. We all wanted to celebrate our city anniversary together and now we have to mourn the dead and injured.”

The German news agency dpa cited unidentified police sources as saying the weapon was believed to be a knife and no one had yet been arrested. The attack happened on a central square, the Fronhof.

The “Festival of Diversity,” marking the city’s 650th anniversary, began on Friday and was supposed to run through Sunday, with several stages in central streets offering attractions such as live music, cabaret and acrobatics.

Solingen has about 160,000 inhabitants.

Germany’s top security official, Interior Minister Nancy Faeser, recently proposed toughening weapons laws to allow only knives with a blade measuring up to 6 centimeters, nearly 2.4 inches, to be carried in public, rather than the length of 12 centimeters which is allowed now.

contributed to this report.