A brave Australian pensioner on holiday in Thailand rescued a family of three including a teenage girl from a burning house.

The humble 'Sheila', who only gave her name as Kim, 65, was heading back home from dinner at a restaurant when she saw the fire breaking out behind a counter in the single-storey concrete office in Krabi on May 15.

Kim tried to push the door open but it was locked. She ran back to the restaurant some 30 metres away and alerted staff to the blaze - before grabbing fire extinguishers and racing back to the inferno.

Kim and the locals used the heavy cylinders to break open the glass entrance of the office, which was divided into a travel agency office and a spa facility, as they battled the growing flames.

Speaking in the video to a local reporter, the hero tourist said: 'When I saw the fire, I went back to the restaurant. It was the computer, electrical, and flame and smoke going out that way. And then everyone ran up and had to use the fire extinguisher to go 'bang bang' on the door and put out the fire.

'There was more flame, but we didn't know people were in there. The mother and her boy came out, but the daughter was still there, and I had to get her out. There were three people who came out. It was more, I think the computer, electrical, caused it.

'It could have been very bad.'

Kim left the scene after the fire had been extinguised and went back to her hotel to sleep.

The family of three, including a 13-year-old girl, were all safe. They were taken to hospital to be treated for smoke inhalation but they were not seriously injured.

Police believe the fire may have been sparked by a short circuit. An investigation into its cause is underway.

Fireman Wat Attawat said: 'The family were sleeping and could have all been killed if the tourist did not wake them up. We are very grateful to her. She noticed there was a fire and saved their lives.'