A bushfire emergency warning has been declared for an out-of-control blaze that has closed the Kwinana Freeway in Perth’s southern suburbs.

Authorities have warned people in the area are in danger from the Baldivis fire and need to act immediately to survive, saying there is a threat to lives and homes

The freeway has been closed in both directions between Mundijong Road and Karnup Road.

The fire started near the intersection of the Kwinana Freeway and Safety Bay Road in Baldivis.

The emergency warning covers an area bounded by Bertenshaw Road, St Albans Road, Folly Road, Young Road, Doghill Road and the Kwinana Freeway on the eastern side of the freeway, and Nyilla Approach, Baldivis Road, Claret Ash Boulevard and Kwinana Freeway on the western side of the freeway.

IF YOU'RE HEADING SOUTH ON KWINANA FWY THE FWY IS CLOSED AT BALDIVIS AND TRAFFIC IS AT A STANDSTILL FROM MORTIMER RD ONWARDS pic.twitter.com/NvDa8nLkMO

— 💜Purrrplegrrrl💜(Neese) (@purrrplegrrrl) June 6, 2019

The alert level for the fire has been upgraded as fire conditions are erratic and it is impacting properties.

The blaze is moving fast in a southerly direction.

It was reported at 9.30am and has so far burnt through more than one hectare of scrub land.

People are being advised to leave if the way is clear, or prepare to actively defend their homes.

The Department of Fire and Emergency Services advises:

• If you are well prepared and plan to actively defend your home, make final preparations now;
• If you are not at home, do not try to return as conditions in the area could be very dangerous;
• Close all doors and windows and turn off evaporative air conditioners, but keep water running through the system if possible;
• Multiple firefighting units are responding to the blaze, the cause of which is unknown.

-ABC