Four fire engines and around 20 firefighters responded to a flat fire on Straight Road, Romford.
Part of the ground floor flat was damaged by the fire. Two adult residents were assessed for smoke inhalation by the London Ambulance Service.
Control officers took the first call about the fire at 2255 and the fire was under control by 0338. Crews from Harold Hill, Romford and Hornchurch attended the fire.
Our Fire Investigators believe the fire was started by discarded smoking materials.