A 40-year-old man is in a critical condition after a house fire at Marion in Adelaide's south-west on Saturday morning.

Emergency services were called to a property on George Street at about 6:30am after reports that a fire had broken out inside the home. Metropolitan Fire Service crews attended the scene and worked to extinguish the blaze.

The fire was contained to the bathroom of the property, according to emergency services. Despite the relatively contained area of the fire, the man suffered serious burns and was taken to hospital for urgent medical treatment.

His injuries have been described as life-threatening.

Fire investigators have attended the property as authorities work to establish how the blaze started. Police have said they do not currently believe the circumstances surrounding the fire are suspicious.

The incident has prompted an emergency response involving firefighters, police and medical personnel in the Marion area.

House fires can develop rapidly, particularly when they occur inside enclosed areas. Smoke and heat can create dangerous conditions even when flames are limited to one part of a property. Fire authorities routinely encourage residents to have working smoke alarms and to leave a burning building immediately rather than attempting to retrieve belongings.

In this case, investigators are continuing to examine the circumstances surrounding the incident. The exact cause of the fire had not been established at the time of the latest report.

Police have also appealed for anyone who may have information about the incident to come forward. Investigators may examine witness accounts and other available evidence as part of determining how the fire began.

The injured man's condition remains critical, making the incident a significant emergency for the local community.

Marion is located in Adelaide's southern metropolitan area and contains a mixture of residential properties and commercial areas. Emergency services regularly respond to residential fires across metropolitan Adelaide, with investigations undertaken after serious incidents to determine their cause.

Authorities have not indicated that the fire was deliberately started, and there is currently no suggestion in the reported information that another person was responsible.

The investigation remains ongoing while the injured man receives hospital treatment.

Residents in the surrounding area are also being reminded of the importance of household fire safety, including maintaining smoke alarms, keeping exits accessible and having a plan for getting outside quickly if a fire occurs.

The incident demonstrates how quickly a residential fire can result in serious injuries, even when firefighters are able to contain the flames to a relatively small section of a property.

Further information about the man's condition and the cause of the fire may become available as emergency services and investigators continue their work.