A bushfire has cut off access to a freeway in Perth, with residents in two suburbs warned to evacuate or find shelter.

An emergency warning has been issued for parts of Aubin Grove and Hammond Park, about 30km south of the city centre.

A number of roads have been closed including part of the busy Kwinana Freeway, the Department of Fire and Emergency Services said on Wednesday.

“You are in danger and need to act immediately to survive,” the warning said.

“Homes in the area are under threat by fire now.”

People in the area have been told to leave immediately if it is safe to do so or find shelter if they cannot.

“Go to a room in your home away from the fire front and make sure you can easily escape,” emergency services said.

“Choose a room with two exits and water such as a kitchen or laundry.”

– AAP