Two teenagers are in hospital with stab wounds and two others have been arrested after an incident in Perth's northern suburbs on Sunday afternoon.

Police were called to the suburb of Karrinyup just after 2.30pm when a member of the public reported that a person had been stabbed, and another person was chasing the perpetrator down the road, in the vicinity of Jackson Avenue.

Around the same time police also received several reports of a person with a bladed weapon seen on Francis Avenue, near the Karrinyup Shopping Centre precinct.

Several ambulances and police units including local police, detectives, the canine unit and police air wing were deployed.

Two 18-year-old men with stab wounds and lacerations were taken to hospital, while two 16-year-old boys were arrested.

Police say inquiries are ongoing but there is no ongoing danger to the community.

The two victims are understood to be in a serious but stable condition in hospital. Police are still confirming the nature of the injuries they received. 

One of the two juveniles taken into custody was also taken to hospital for treatment of a hand injury, but was later released to police.

Bewildered locals watched the events unfold as police captured those involved including one young man hiding in a garden.

Local resident Geoffrey Mosel spoke of seeing police drawing their guns and making an arrest.

"They were hovered over this person and then we saw them collect him and handcuff him," he said.

He says the incident came as a shock.

"You just feel vulnerable, a little bit," he said.