Police search for assailant after 'knife attack' at Westfield Carousel ...

Police are searching for two men after an apparent knife attack at a major Perth shopping centre on Friday afternoon.

Police were called to Westfield Carousel in Cannington at around 3:30pm after receiving reports of an altercation between the two men.

They initially said a 20-year-old man had been slashed in the face with a knife by another man, who fled the scene. 

On Friday evening police said a third man was involved in the incident and a second knife was had been recovered from the scene.

They are looking for two males, and now say it is unclear how the victim was injured. 

Police say there is no ongoing threat to the public "or further cause for alarm".

Westfield Carousel is one of Perth's largest shopping centres. (Supplied: Wikipedia)

The incident occurred almost a month after Joel Cauchi stabbed and killed six people and injured 12 at the Westfield Bondi Junction shopping centre in Sydney.

WA Police Inspector Geoff DeSanges said it was understandable people had been shaken by Friday's incident.

"Considering what's occurred in the eastern states, in Bondi in recent times, and other reports of knives in our community, it's completely understandable that people would be concerned," Inspector De Sanges said.

He said police were still working to determine whether the men were known to each other. 

People had earlier been asked to avoid the area, while shoppers inside the centre were told to be aware of their surroundings and report any suspicious behaviour.

Retail workers who spoke to the ABC said stores are now re-opening after some shops were instructed to close their doors.

It is unclear whether all stores in the shopping centre were instructed to temporarily close.

Some stores have chosen to remain shut for the rest of the day.

Westfield Carousel is about 12 kilometres south of Perth's CBD and is one of the biggest shopping centres in the metropolitan area.