Four fire engines and around 25 firefighters were called to a fire at a maisonette on Cator Street in Peckham.
A room on the ground floor of a maisonette split over three levels was completely destroyed by fire. Two men and one woman left the property before the Brigade arrived. One woman and one man were suffering from smoke inhalation and were taken to hospital by London Ambulance Service.
A London Fire Brigade spokesperson said: “Thankfully the residents had working smoke alarms, which alerted them to the fire in the early hours of the morning. This incident is a timely reminder of just how important it is to have working smoke alarms in your home.
“Smoke alarms give the earliest possible warning when a fire starts. We encourage everyone to have smoke alarms fitted in every room where a fire could start, plus a heat alarm in the kitchen. It’s important to test them regularly.
"Firefighters recommend that you have a look at our online Home Fire Safety Checker to make sure there are no hidden hazards in your home.
"The online tool will ask you a series of questions that will help us work out the level of risk in your home, or the home of someone you care for. It only takes a few minutes to get tailored advice to keep yourself and loved ones safe from fire.”
The cause of the fire is undetermined.