An explosion at an outbuilding in Heston on Tuesday morning is being investigated by police.
Firefighters were called to a property in Ash Grove, just off Springwell Road, at 6.18am to reports of a fire and explosion.
A London Fire Brigade spokeswoman said the blaze had already been extinguished and unknown occupants had left the scene by the time the crew from Feltham arrived.
She added that there was 25% damage to the single-storey garden dwelling and said police had also been called to investigate.
No one is believed to have been injured in the fire, which one resident said started at 4.30am. The cause is not known at this stage.