SOLINGEN, Germany (AFP) — German police on Saturday extended a major manhunt after a man stabbed to death three people and wounded eight others at a street festival in the city of Solingen.

Police closed off the center of Solingen, while victims and witnesses were being questioned about the attack on Friday night, according to a statement which said five of the injured were in “serious” condition.

Special forces were among security personnel in the city center while a helicopter flew overhead, according to an Agence France-Presse journalist.

“An unidentified man attacked several people with a knife around 9:40 p.m.,” said the statement released by police in the nearby city of Duesseldorf.

“Police are currently searching for the perpetrator with a large contingent,” it added, encouraging witnesses to submit photos, videos and any other information about the attack.

Solingen is a city of some 150,000 people located between Duesseldorf and Cologne.

People had gathered in the town on Friday evening for the first day of a three-day “Festival of Diversity.”

It was set to feature music, street theater, variety shows and comedians in the city center and several other areas, it said.