Elderly man killed after gas bottles explode inside home

An elderly cancer sufferer has been killed in a gas explosion at his home in Adelaide's east.

Firefighters say four 9kg gas cylinders – three inside the home – exploded at the St Morris unit just before 7am today.

A heroic neighbour, identified only as John, tried desperately to save 71-year-old Bob Baksa from the burning unit but sadly he couldn't reach him.

John was taken to the Royal Adelaide Hospital suffering smoke inhalation.

Elias Anargyros was among other neighbours who heard the blast and rushed to help.

"Came outside, wall of flames," he said.

"The roof was on fire, just smoke billowing out, residents came pouring out from all the houses."

"People were trying to fight the fire with hoses and that but it was just hopeless," another neighbour, Colin, said.

David Lines remembered Bob as a "nice gentleman" with a "good heart".

"We all loved him and yeah, sadly missed," he said.

He said Bob had been battling cancer.

"He's not well and he can't hardly walk and he's got problems breathing."

The Metropolitan Fire Service praising John's actions.

"The efforts of a person trying to help out there has been nothing short of heroic," Declan Dwyer said.

"To just jump in and help out wherever possible, that's something that we really admire."

He says investigations are continuing into how the cylinders came to explode.

"At this stage we're still investigating what the gas was being used for but using gas cylinders inside a property is obviously very dangerous," he said.

"To have an apartment explosion like that and have no one else hurt is pretty remarkable."