A South Australian electrician has been left with significant burns after an explosion was sparked from a fridge he had been called to repair inside a shopping centre.

The contractor had been called to the Yummy Fish restaurant in Salisbury, in Adelaide's north, when a ball of flame rattled through the store.

"All of a sudden, you just hear a big woof and half of their shop's on fire," Christine Wilkinson, who works in a nearby Telstra store, told 9News.

The electrician was seen being doused in water following the explosion. (9News)

"They were just running to get away from the flames and everyone was moving away."

CCTV vision of the incident shows workers rushing to grab fire extinguishers before the electrician ran out clutching a gas bottle.

"I was amazed at how calmly and quickly he acted, despite his injuries," Tom Calderwood, a worker at the store, said.

CCTV vision of the incident shows workers rushing to grab fire extinguishers before the electrician ran out clutching a gas bottle. (9News)

Firefighters say the cause of the explosion remains unclear. (9News)

"You could clearly see burns, skin blistering on his face."

The electrician suffered full body burns to his chest and face, while the owner of the shop also received burns to his legs.

Both men have since been taken to the burns unit at the Royal Adelaide Hospital.

Firefighters say the cause of the explosion remains unclear.

"They were working on a compressor. It was a flash event that occurred and was immediately extinguished," David Potter from the Metropolitan Fire Service told 9News.