The perpetrator of the attack has been arrested. A motive for the stabbing, which occurred in the city's historic center, is still unclear, with many of the victims having been foreigners.

Four people were seriously injured after a stabbing incident in Amsterdam's city center on Thursday.

Witnesses said the suspect was stabbing people at random on Sint Nicolaasstraat, near Dam Square.

Police said the suspect had been detained.

An attack in the heart of historic Amsterdam

At least four people were stabbed at around 3:50 p.m. (1450 UTC), police said.

"Four people were injured here, seriously injured. And a suspect was arrested, who was also injured," a spokesperson for the Amsterdam police told journalists.    

The alleged perpetrator of the attack was described as young man with short blonde hair.  

Many of the victims are foreigners, possibly tourists from abroad who were visiting the city. 

"Among the victims are a 67-year-old woman and a 69-year-old man, both American nationals; a 26-year-old man from Poland; a 73-year-old woman from Belgium; and a 19-year-old woman from Amsterdam," Dutch police said. 

Bystander overpowered perpetrator, injuring him 

One witness told Dutch media that the attacker had stabbed a young woman in the back, with the perpetrator then running away. 

"I saw a knife at least 10 centimeters (nearly four inches) sticking out of the girl's back, between her shoulders," they told Amsterdam newspaper Het Parool. 

Dutch authorities said a bystander overpowered the suspect during the attack, with the alleged perpetrator taken to the hospital because of "an injury to his leg."