Mirrabooka police officers confirmed the leak occurred when the driver of a gas tanker hit a wall as he was leaving the Caltex petrol station on January 11, rupturing a valve on the tank.
The City of Stirling set up an evacuation centre at its civic centre.
A DFES spokeswoman said officers received a request about 8.25pm before evacuating shoppers at Northlands Shopping Centre on Amelia Street and surrounding residents within a 250m zone of the Amelia Street and Wanneroo Road intersection.
“Three fire trucks attended the incident and the gas tanker was eventually recovered to a safe location,” she said.
Residents were able to return home about 12.15am.
A police spokeswoman thanked residents, who were inconvenienced, for their patience.