Maddington residents were forced to evacuate their homes last night before police arrested an armed man inside a suspected drug lab.
Police spokeswoman Ros Weatherall said the Tactical Response Group was called to a house on Kenwick Road after reports a man with a firearm was holed up in a house.
Officers evacuated neighbours and cordoned off the area before arresting a 38-year-old man, Ms Weatherall said.
She said the alleged offender followed police instructions without any confrontation.
Police searched the house and a shed and discovered a hydroponic cannabis set-up and a  gas bottle containing ammonia.
Ammonia is used to manufacture methamphetamine.
Fire and rescue services also attended the scene.
The man was charged with cultivating a prohibited plant with intent to sell and supply.
Last night's arrest was the third suspected drug lab in the past two weeks which police have uncovered.
A pilot was arrested on Friday after police found chemicals and glass instruments used for making drugs inside a hangar at Jandakot Airport.
On October 29, a woman was charged in relation to a suspected drug lab in Huntingdale where residents were also forced to flee their homes.