A police spokesman said: 'The cause of the explosion has yet to be determined, however it is being treated as suspicious at this early stage.'
Initially the incident in South Harrow was blamed on a gas explosion, but a full police investigation was launched under the leadership of Det Chief Insp Colin Sutton after the body was identified beneath the ruibble.
Two people were also injured and taken to hospital for treatment.
Six crews from London Fire Brigade were sent to the incident in Stanley Road, South Harrow at around 9.40pm on Wednesday night after the blast destroyed two houses and damaged another.
A fire brigade spokesman said: “Two residential properties on the road have collapsed. Two people were taken to hospital and following a search of the premises the body of a man was discovered.”
Around 30 fire fighters worked through the night alongside contractors to stablise the structures.
Surrounding roads and properties were sealed off while the scene was being made safe and fire fighters used specialist listening equipment to search the rubble for any other casualties.
A London Ambulance Service spokesman confirmed a 26-year-old man suffering from a serious head injury and a 17-year-old girl, suffering from 20 per cent burns, had been taken to hospital.
A National Grid spokeswoman said: “It could be some time before we know exactly what has happened.'