Customers have been turned away from Bunnings in Willetton where a police shooting unfolded on Saturday night.
The store reopened for a few hours on Sunday morning before shutting again as the investigation into why a 16-year-old boy stabbed a man before being shot by police continued.
A blood stain could still be seen in the car park on High Road, despite being washed down by officers.
The teenager allegedly stabbed a man aged in his 30s, who remains in Royal Perth Hospital in a serious but stable condition, just after 10pm on Saturday night.
Officers were called to the car park after a call from the teenager himself and found the boy holding the knife.
Police Commissioner Col Blanch said two officers withdrew their Tasers, while a third took out their firearm, confronting the lone teenager.
After officers called for the teenager to put down his weapon, understood to be a 30cm kitchen knife, the teen rushed the officers, who deployed both their Tasers, Commissioner Blanch said.
When the boy turned on the third police officer, he discharged his firearm, fatally wounding the teenager.
Police at the scene worked through the night and wrapped up their initial investigations on Sunday around 7.30am as volunteers from a sporting group set up a sausage sizzle.
But around 10.30am, the fundraising tent had been dismantled and customers were being turned away from the usually jam-packed hardware store, with a security guard telling would-be shoppers that there had been an incident overnight.
Three detectives went inside, emerging some 20 minutes later.
Bunnings confirmed the store was temporarily closed as staff continued to assist police with enquiries and worked to re-open as soon as possible.
A sausage sizzle volunteer, who did not want to be identified, said police told him the incident involved two people yelling at each other.
The teen and his victim had apparently emerged from the nearby Zap gym – which is unstaffed, with entry only available to members via swiper card – and argued as they moved through the Bunnings carpark, he said.
“They were yelling out at each other then next minute there’s a stabbing,” the volunteer said.
“It’s not the place for something like that to happen here. Willetton’s very quiet — there’s no pubs here.
“So there’s obviously something happened in the gym, then to have an argument then spilling out here.”
By sunrise, the huge police presence had reduced to a forensics van and three officers peering into bins with their torches, the man said.
The incident delayed staff at the round-the-clock Sai Vet Hospital from going home at the end of their shift on Saturday night.
High Road residents Ameya and Gouri Khandekar, who have lived near the Bunnings for the past three years, heard sirens but thought nothing of it in the otherwise quiet suburb.
“It’s scary,’ Ms Khandekar told reporters.
“I have two boys and my older one’s 12 who’s just started to go to high school and you have to be careful with what they watch … watching things online.
“Because of the school zones, it’s a very family-oriented suburb. Quiet, friendly – the reason we’re here.”
Mr Khandekar said it was “quite shocking” to have such a crime on his doorstep following a recent spate of knife attacks including the Bondi Junction stabbings.
“It’s always been a good place. Qualified, educated people,” he said.
“You have a home open and it’s usually, within a couple of days, under offer.”