Firefighters have extinguished a unit fire in Kaleen overnight.

At approximately 9.40pm ACT Fire and Rescue received 12 triple zero calls to a unit alight on Baldwin Drive.

Firefighters arrived within 12 minutes of the initial call to find a second story unit with flames through the roof and windows.

Firefighters commenced an internal attack on the fire and were able to rapidly knock down the fire.

Several people self-evacuated with some receiving assistance from ACT Policing to relocate to a safe area of the complex.

Four residents were assessed By ACT Ambulance Service Paramedics at the scene but did not require transport to hospital.

Extensive damage has occurred to the unit where the fire originated with up to a further 14 units affected by smoke and water damage.

The cause of the fire is believed to be accidental.