Sydney house erupts in flames in suspected arson attack

Four people have been hospitalised following a suspected arson attack.

More than 40 firefighters with 10 fire trucks battled the blaze at Abbotsford in Sydney's inner west.

Police are searching for a "person of interest" and a red Holden Astra reported as leaving the scene.

Police are searching for a man who was wearing a balaclava when he started a fire in a Sydney home that led to four people being hospitalised and took dozens of firefighters to extinguish.

Emergency services were called to Abbotsford in Sydney's inner west about 4:20am on Tuesday following multiple Triple Zero (000) calls about a house fire.

Fire and Rescue NSW Acting Superintendent Peter Murray said 40 firefighters with 10 trucks worked to contain the "rapidly expanding fire".

"They've done well to contain it, primarily to the house involved, although the fire has spread to an adjoining house," he said.

"Fire crews were able to cut the fire off inside that house, although it has also been damaged."

An 88-year-old woman, her son and his wife were taken to hospital and treated for smoke inhalation.

A 49-year-old man, who climbed a ladder to save the elderly woman, was also taken to hospital.

Another man, who police said was a long-term renter at the home, was treated but did not require hospitalisation.

NSW Police Superintendent Christine McDonald said the fire was being treated as suspicious, but at this stage police were unsure whether the attack was targeted.

"We are working very closely with the occupants of this house. We do not believe they are criminally linked," she said.

Superintendant McDonald said police were looking for a man who fled the scene in a red Holden Astra and was wearing a balaclava.

She said he was believed to have used an accelerant and had suffered burns.

"A neighbour so bravely confronted that person whilst they were setting the house alight, and they managed to get away from the scene."

Superintendant McDonald praised the efforts of bystanders and first responders.

"The police officers that arrived on scene, one of them graduated in August this year ... and he scaled a ladder whilst the house was completely alight."

Police are canvassing nearby Blackwell Point in which the red car was seen headed towards.

They have urged anyone living within the vicinity of Great North Road in Abbotsford to Lyons Road in Russell Lea to check any CCTV.

Acting Superintendent Murray said crews on Tuesday morning were still working to fully extinguish the flames at the main house before the scene was handed to police.