Police officers stand at a cordon in the city centre in Solingen, Germany, on Saturday. AP

Three people were killed and four severely wounded in a knife attack at a festival in the western German city of Solingen, police said, with the search for the suspect dragging on into Saturday morning.

A police spokeswoman in nearby Duesseldorf told the media early on Saturday that the ongoing manhunt extended beyond Solingen, and that numerous roadblocks had also been set up around the city.

So far, there was still no detailed description of the suspect, with police seeking information about the Friday night attack -- including photos and videos -- via an online portal, the spokeswoman said.

In the immediate aftermath of the attack, there was a large police presence at the scene including special forces and a helicopter, according to an AFP photographer.

The attacker had "stabbed people indiscriminately with a knife", the Bild daily reported.

Police cars cordon the scene early on Saturday. AP

The festival was part of a series of events to celebrate the city's 650th birthday.

In a statement posted online, Tim-Oliver Kurzbach, the mayor of Solingen, said the whole city was in "shock, horror and great grief".

"We all wanted to celebrate our town's anniversary together and now we have to mourn the dead and injured," he said.

‘Brutal and senseless’

Kurzbach thanked the emergency services for their work at the scene and expressed sympathy with those who had witnessed the attack.

"It tears my heart apart 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," he said.

Hendrik Wuest, the premier of North Rhine-Westphalia state, also expressed his "shock and grief" in a post on social media platform X.

"An act of the most brutal and senseless violence has struck at the heart of our state," he said.

 North Rhine-Westphalia state's interior minister, Herbert Reul, visited the scene early on Saturday. He told reporters it was a targeted attack on human life but declined to speculate on the motive.

Herbert Reul, Minister of the Interior of North Rhine-Westphalia, speaks to the press early on Saturday. AP

"The whole of North Rhine-Westphalia stands by the people of Solingen, especially the victims and their families."

Solingen is a city of some 150,000 people located an equal distance from Duesseldorf and Cologne.

People had gathered in the town on Friday evening for the first day of a three-day "Festival of Diversity", according to the event's website.

The festival was set to feature music, street theatre, variety shows and comedians in the city centre and several other areas, it said.

Up to 75,000 visitors had been expected to attend over the three days.

Festival cancelled

The Solinger Tageblatt newspaper reported that one of the co-organisers of the festival had come on stage to call off the event.

The crowd were also asked to leave the city centre, it said.

Following the announcement, thousands of attendees cleared the area, the paper reported, with a journalist at the scene describing the atmosphere as "ghostly".

Police members and forensic experts scan the affected area following the incident in Solingen. Reuters

"People left the scene in shock, but calmly," Philipp Mueller, one of the organisers, told the newspaper.

A witness who spoke to the Tageblatt said he was a few metres from the attack, not far from the stage, and "understood from the expression on the singer's face that something was wrong".

"And then, a metre away from me, a person fell," said the man, Lars Breitzke, who at first thought it was someone who was drunk.

But when he turned around, he saw other people lying on the ground and several pools of blood, he added.

Festival organiser Mueller later told the Tageblatt that the rest of the festival would also be cancelled.

"We've just informed all the artists and stand operators," he said.

Germany has seen a series of knife attacks over the past 12 months, with Interior Minister Nancy Faeser promising to crack down on knife crime.

A police officer was killed and five people were wounded in a knife attack at a far-right rally in the city of Mannheim in late May.

Agence France-Presse