A nearby resident told the Daily Star that they were woken by “a massive bang”.
London Fire Brigade was called to the scene at 7.08am.
In a statement, the service said: “Six fire engines and around 40 firefighters have been called to a fire and explosion on Galpin’s Road in Thornton Heath.
“A terraced house has collapsed following an explosion.
“The Brigade’s 999 Control Officers have taken 13 calls to the incident.
“The Brigade was called at 0708. Fire crews from Norbury, Mitcham, West Norwood, Woodside and surrounding fire stations attended the scene.
“The cause of the fire and explosion is not known at this time.”