A mass stabbing incident at a festival in the western German city of Solingen has left three people dead and five seriously injured.

Witnesses alerted police on Friday night, local time, to an unknown attacker having wounded several people indiscriminately with a knife at near the Fronhof, a central square in Solingen.

Police confirmed the perpetrator was a single, unidentified man who remained on the run.

One of the festival organisers, Philipp Müller, appeared on stage and asked festival-goers to "go calmly" but advised them to "keep [your] eyes open, because unfortunately the perpetrator hasn't been caught". 

Police have confirmed three fatalities and earlier put the number of seriously injured at five. 

But the region's top security official, Herbert Reul, gave a figure of six seriously injured as he visited the scene in the early hours of Saturday.

"I can't say anything about the motive now", Mr Reul said, before adding it was not clear who the assailant was, but that they left the scene "relatively quickly".

"The #Polizei is deployed with a large contingent and is searching for the fugitive perpetrator," a statement from police said on social media platform X.

German news agency dpa cited unidentified police sources as saying the weapon was believed to be a knife. 

Mr Müller said that many people had been wounded by "a knifeman" when he appeared on stage earlier in the evening. 

The Festival of Diversity, marking the city's 650th anniversary, began on Friday and was supposed to run through Sunday.

Solingen has about 160,000 inhabitants and is located in Germany's most populous state North Rhine-Westphalia, between the bigger cities of Cologne and Duesseldorf.

Mayor Tim Kurzbach paid tribute to those killed in a post to the city's Facebook page, SPD Solingen.

"This evening we are all in Solingen in shock, horror and great sadness," he wrote.

"It breaks my heart that there was an attack on our city. I have tears in my eyes when I think of those we have lost. I pray for all those who are still fighting for their lives." 

Mr Kurzbach's statement added the attack took place at a market square where live bands were playing.

Fatal stabbings and shootings in Germany are relatively uncommon.

In June, a 29-year-old policeman died after being stabbed in Mannheim during an attack on a right-wing demonstration.

There was a stabbing attack on a train in 2021, which injured several people.

The German government has been aiming to toughen rules on knives that can be carried in public by reducing the length allowed from 12 centimeters to 6 centimeters.

ABC/wires