Two adults and five children were taken to hospital with carbon monoxide poisoning from a house on High Street in Harlesden, last night.
The occupants left the property before the arrival of the Brigade and were treated on the scene by London Ambulance Service before being taken to hospital.
Seven people were evacuated from adjacent properties as a precaution and crews shut down the gas supply to the property before handing the scene over to the police.
The Brigade was called at 2324 and the incident was over at 0026. Fire engines from Park Royal and Willesden fire stations attended the incident.