Firefighters are battling an out-of-control bushfire in Perth's Kings Park which police are treating as suspicious.
Emergency services warned people in and near the park they should leave the area immediately or be prepared to defend their homes.
"There is a possible threat to lives and homes as a fire is approaching in the area and conditions are changing," an alert from the Department of Fire and Emergency Services (DFES) says.
WA Police said they were advised of multiple fires in the park about 2.50pm AWST on Tuesday.
"At this stage the cause of the fire is being treated as suspicious and Arson Squad are investigating," police said in a statement on Tuesday night.
"Early indications suggest there are multiple ignition points."
The bushfire is moving northeasterly, with multiple roads closed in the area.
More than two dozen fire crews are on the scene and a bushfire watch and act alert is also in place for people in the surrounding area west of the city, DFES said.
"It is not contained or controlled (and) firefighters are on the scene, actively fighting the fire.
"Although there is no immediate danger you need to be aware and keep up to date in case the situation changes."
Local resident Gareth Hayes said ash was dropping around his house about two kilometres from the park in the suburb of Subiaco.
"There are helicopters buzzing about and I can see a big plume of smoke drifting west away from the park," he said.
Cafe owner Connie Tuang said fire trucks had rushed past her business in nearby Nedlands.
"The air is thick and I can smell the fire," she said.
A DFES alert says the park has been closed but a worker at a health club in the park said it remained open and she was worried about her asthma.
WA Police urged anyone with information on the fire to come forward and said rewards of up to $25,000 were available for intelligence that leads to a conviction.
It's the second bushfire in Perth's inner suburbs this week, with firefighters on Monday called to a blaze in Bold Park, which is also largely bushland and is 437ha in size.
Kings Park is one of the world's largest inner city parks and is about 400ha in size and 10km around.
It is located in the west of the Perth CBD on Mount Eliza and is a mixture of bushland, botanic gardens and grassed parklands.
It's also a popular tourist spot, with panoramic views across Perth from Mount Eliza, an outdoor cinema, a historic tennis club and restaurants.
The park is also home to the State War Memorial and is surrounded by hospitals, apartment buildings, family homes, busy inner-city roads and office buildings.
