Hundreds of people were told to stay indoors or leave their homes when a fire broke out overnight.
About 80 residents were taken to Ealing town hall in the early hours of Friday after a rubbish fire started behind a row of shops in South Ealing Road.
The surrounding area was evacuated as fire crews worked to cool a gas cylinder at the back of the building.
Little Ealing Primary School and Mount Carmel Catholic Primary School have also been closed for the day.
South Ealing Road is closed at Popes Lane and buses are being diverted away from the area.
A spokeswoman for Ealing Council said the evacuation affected 500 homes and a total of 100 people chose to leave their properties, with 80 taking refuge in the town hall.
The cordon is expected to stay in place until 0100 BST on Saturday.