Police are investigating whether a series of destructive mini-tornadoes may have contributed to the deaths of two young Beaconsfield men with muscular dystrophy.
Housemates Conor Murphy and Kyle Scolari, both 25, were found dead about 7.30am yesterday.
A police spokeswoman said the men had conditions that required medical assistance.
"The deaths are not being treated as suspicious and the investigation will include inquiries relating to the electronic medical equipment they relied on," she said.
The medical equipment that the two 25-year-olds depended on didn't have back-up electricity after the tornado downed power lines, their grieving friend says.
Their coach and close friend Hayden Stevens says the men had some independence, playing sport and taking part in social activities, but when they slept, they were dependent on a machine that helped them breathe as they lay flat in bed.
“Unfortunately when the power goes out, the machine doesn't have the back up supply and your bed doesn't work so they couldn't get their beds up so they were stuck flat,” Mr Stevens told Fairfax radio on Tuesday.
“Their beeper turned off and unfortunately, they couldn't rouse the carer.
“It was completely out of the blue to wake up and hear that a storm had ... taken them from us.”
Mr Stevens, who also has muscular dystrophy, said the condition was tough to live with and required attentive carers.
“It takes all your muscle movement so you're pretty much confined to your electric wheelchair. You can't lift your arms up. You really can't do anything for yourself so the carer is pretty much what's keeping you alive.”
He said Mr Scolari and Mr Murphy's soccer teammates, who recently competed with them in a national competition, were in shock.
The men's home was one of 12,000 properties that lost power in Perth's southern suburbs after power poles and power lines were felled in the storm.
Western Power workers scrambled to restore power to houses in Willetton, Hilton, O'Connor, Booragoon and Beaconsfield, while an army of more than 80 State Emergency Service volunteers responded to 82 calls to clear debris and patch up damaged roofs.
The Weather Bureau estimated wind gusts of up to 120km/h lashed Hilton and surrounding southern suburbs.
The strongest winds recorded were on Melville Water, where gusts reached 87km/h at 5.45am.
Another system hit the western suburbs, damaging homes in Claremont.
In an online post early this year, Mr Murphy wrote he had a variable positive airway pressure machine and cough machine on a table next to his bed.
He wrote that if he needed anything during the night an audio monitor in his room would alert his carer, who would then check on him.
"I actively seek out emerging assistive technology, either through support staff or by researching online, because the products and devices I use make my day-to-day living much easier and more independent," Mr Murphy wrote.
It is understood the pair's home had a back-up generator but it failed.
A Western Power spokesman said the electrical provider was assisting police with their investigation.
The SES got calls from Hilton, Beeliar, Claremont, Nedlands, Melville and surrounding suburbs, mostly because of damaged roofs or fallen trees.
According to the Weather Bureau, the cold front that passed over Perth between 5am and 7am combined with just the right conditions to trigger mini-tornadoes.
Central to those conditions was "just enough" atmospheric instability and "just enough" windshear - a term used to describe changes in wind speed and direction in the different levels of the atmosphere.
Duty forecaster Sarah Fitton said the likely occurrence of tornadoes was particularly difficult to predict, as was their behaviour.
She said although the South West did not get tornadoes of the intensity of those in the US, it was one of the most tornado-prone parts of Australia.
Mr Murphy's mother Lesley posted online yesterday afternoon about her son's death.
"It's with great sadness we wish to advise you all of the passing of Conor Murphy this morning. He passed away peacefully as he slept, knowing that he was loved by you all," she said.
The Federal member for Fremantle Melissa Parke said the death of Mr Murphy, who worked in her electorate office, was "totally tragic".
"He was a wonderful member of our team and he's a great example of how people with disability can contribute to the workforce in the same way as anyone else," she said.