Police are "very confident" of catching an arsonist who poured accelerant over three marked police cars in Fremantle and set them on fire.

Key points: The three marked police cars were doused in accelerant and set on fire

The three marked police cars were doused in accelerant and set on fire The cars were parked in front of the Fremantle police station

The cars were parked in front of the Fremantle police station Police have CCTV footage of a person of interest

The cars were parked in front of the Fremantle police station when they were set alight, completely destroying them.

CCTV footage clearly shows a man inside a nearby petrol station and then later walking away from the scene carrying a small fuel can.

Officers in the station saw the flames coming from two secure police vans and one sedan parked on Leake Street, behind the station, and called fire fighters at 11.10pm.

Nobody was injured and police say the station remains fully operational and did not need extra police cars brought in from elsewhere.

The Arson Squad is leading the investigation and officers are searching for a man aged about 25, of thin-to-medium build with short dark hair and a goatee.

CCTV footage of a man wanted for questioning after three police cars were torched in Fremantle. ( Supplied: WA Police )

Commander Greg Knott said the man could be very clearly seen in the CCTV footage and police would catch him.

"[I'm] very confident. If that person is watching this now, I would encourage that person to surrender to police because we will find you," Commander Knott said.

"It is only a matter of time."

He is asking any member of the public who saw suspicious behaviour in the area at the time to report it to police, as well as anyone who may have dash cam footage.

Commander Knott said he was disturbed someone would do this to police property.

"It's definitely a brazen attack and those are the reasons why we need to review our security," he said.

"We need to have a look at our parking arrangements down there at Fremantle, and our other facilities across the State."

The cars were completely destroyed in the blaze. ( ABC News: Benjamin Gubana )

Police have not put a dollar figure on the damage yet, but Commander Knott said the cars were completely written off.

Police computers, uniforms, police radios and medical kits inside the cars were also destroyed.