Bushfire threat in Perth's east

There is a possible threat to lives and homes from a fire burning in Perth's east.

A bushfire watch and act alert is in place for people near Bailup Road, Toodyay Road and Burma Road in Bailup in the Shire of Mundaring.

Affected communities need to leave or get ready to actively defend their properties, the Department of Fire and Emergency Services says.

The blaze was reported about 4pm on Monday and was caused by lightning.

Meanwhile, lives and homes are no longer in danger from a bushfire burning in the Perth hills but residents are being warned to remain vigilant.

A watch and act alert has been downgraded to an advice for people in Araluen Estate in Roleystone after fire crews managed to bring the blaze under control.

The bushfire burnt through about four hectares and its cause is unknown.