Updated 

Two men have died after an explosion at a Perth shopping centre where they were carrying out electrical maintenance.

Two other men were seriously injured in Tuesday’s blast, after which witnesses reported seeing people running from the scene on fire.

Police said it was believed all four men were working near an electrical transformer at the rear of a Woolworths supermarket at Galleria Shopping Centre in suburban Morley at around 9.30am.

Witness, Jonathan McDonag,h described the scene as horrific, panicked and rushed.

“I came driving in and saw three people come running out … they were on fire,” he told AAP.

McDonagh was among several people who helped the injured, taking off his shirt and using it to put out the flames. Other bystanders were dousing the men with water.

Another witness said: “It was just `whoosh’ and then there were these guys coming out and hitting the deck and then ripping their gear off.”

Stephen Beer from Federation Centres, which manages the Galleria, said the accident occurred during routine electrical maintenance.

The exact cause of the explosion is unknown but lightning has been ruled out, and EnergySafe and WorkSafe are investigating.

The three injured men were rushed to Royal Perth Hospital in a critical condition with serious burns.

One of the men had burns covering 80 per cent of his body and was conscious and breathing when paramedics attended.

Hours later, police said the man had died.

A woman who was trying to assist the injured suffered smoke inhalation and was taken to Sir Charles Gairdner Hospital.

Several other people were treated for shock and smoke inhalation on the spot, but didn’t need to be taken to hospital.

The Department of Fire and Emergency Services has cordoned off the scene.

Beer said a large section of the centre, the Woolworths/Target mall, would remained isolated and closed for the time being.

A Woolworths spokeswoman stressed the explosion did not occur in the supermarket or areas managed by Woolworths.

“Our thoughts are with those injured as well as with the family and friends,” she said.

AAP