Firefighters said they received 13 calls to the incident.
In a statement, the London Fire Brigade said: “Six fire engines and about 40 firefighters have been called to a fire and explosion on Galpin’s Road in Thornton Heath.
“A terraced house has collapsed after an explosion and adjacent properties have also been damaged. One person has been released from a neighboring building.
The Brigade’s 999 control officers took 13 calls to the incident.
The brigade was called up at 0708. Fire crews from Norbury, Mitcham, West Norwood, Woodside and surrounding fire stations arrived on the scene.
“The cause of the fire and explosion is unknown at this time.