The four victims were rescued from the property by fire crews but they all died at the scene.
Two women and two children have died in a house fire in south-east London.
The four victims were rescued from the first floor of the property in Hamilton Road, Bexleyheath, but all died at the scene, London Fire Brigade said.
LFB said it was called at 20:28 GMT and the fire was extinguished by 21:45.
A man who left the property before firefighters arrived was taken to hospital by the London Ambulance Service, it added. The cause of the fire is under investigation.
About 40 fire-fighters and six fire engines from Bexley, Erith, Plumstead, Lee Green and Sidcup fire stations attended the scene.
The London fire commissioner Andy Roe said: “This is a truly terrible incident which is both sad and shocking. Our thoughts are with the family, friends and local community at this difficult time.”