Elderly woman alone when Molotov cocktail thrown at her Adelaide home

A 72-year-old woman was treated for smoke inhalation after a Molotov cocktail was thrown at the Adelaide home she shares with her son.

Janelle Gaston, who suffers from dementia and epilepsy, was alone in the home on Cuming Street when the attack took place just before 5am.

Her son Ronald rushed home to be by her side.

"It is pretty scary, knowing that she's defenceless and that I wasn't here," he said.

"I was shaken up a bit when I first got here. It makes me angry to think that I could be targeted."

Witness Zara Goss said she had been asleep when she was woken by "a yell and a bang".

The front of the brick house was engulfed by the flames, but fire crews were quickly on scene and brought the blaze under control in minutes.

Police are now investigating.

Ronald said he had been living in the house for seven years, and his mother had moved in six months ago.

He said they'd never had any trouble.

"I don't have any enemies, I just don't understand," he said.

"I reckon it'll have to be mistaken."

Neighbours also said it was a normally quiet street.