Two children and two women - all believed to have been related to each other - have died in a house fire.
Six fire engines, around 40 firefighters and a team of paramedics were called to the blaze in Hamilton Road, Bexleyheath at 8.30pm on Thursday.
The police cordon in Hamilton Road this morning
Crews in breathing apparatus rescued two women and two children - believed to be an infant boy and girl - from the first floor using a nine metre ladder. All four died at the scene, the London Fire Brigade said.
A man who left the building before firefighters arrived has been taken to hospital.
The cause of the fire is under investigation.
“This is a truly terrible incident which is both sad and shocking,” said London Fire Commissioner Andy Roe.
“Our thoughts are with the family, friends and local community at this difficult time.”
In a statement, Mayor of London Sadiq Khan said he was “heartbroken” to hear of the news.
He said: “I am heartbroken to hear that two women and two children have tragically lost their lives in a house fire in Bexley last night. My heart goes out to all their loved ones and the local community at this awful time.
“The London Fire Brigade worked tirelessly at the scene to put out the fire and I remain in close contact with them over their urgent investigation into this terrible incident.”
A resident of Bristow Road, which is two streets away, said: "I was shocked to see what happened. I went to pick up my wife from work at the station and the whole road was closed off.
"My friend living close by said there had been a major fire."
The man, who did not want to be named, added that he and his partner had gone to view the property recently when it had been on the market but had not met the current occupants.
Another resident, who lives behind the property in Herbert Road, said they were alerted to the blaze after hearing sirens on their way to the bathroom.
She said: "We didn't even smell the smoke that is the ironic thing about it. I just thought it was a car crash on Pickford Lane."
This morning, Hamilton Road remained blocked off in both directions with a police cordon in place at both ends.
At the junction with Pickford Lane, two police officers were standing guard and a police van and fire engine remain at the scene.
Throughout the morning, mourners have been pulling up in cars along the busy main road to pay their respects and several floral tributes have been laid.
LFB commissioner Matt Cook provides an update
One tribute read: "My heart aches for the loss of precious life. To your family."
Another added: "Thinking of you all at this sad time."
In a statement issued this morning, Met Police said the victims' next of kin had been informed and were receiving specialist support.
A spokesman said a man remained in hospital with injuries to his legs. His condition was not thought to be life-threatening.
A further person was taken to hospital by London Ambulance Service after he arrived at the scene.
At this early stage, the cause of the fire is not thought to be suspicious and there have been no arrests.
Speaking from the scene this morning, London Fire Brigade deputy assistant commissioner Matt Cook, expressed his condolences to the family and friends of the victims.
He said: "Due to the severity of the incident we mobilised six appliances from the surrounding area. Those six appliances arrived very very quickly.
"They were at the scene very very quickly and carried out the rescues.
"We currently have specialist investigating officers from our fire investigation teams on the scene and we are working closely with the Metropolitan Police Service and local specialist investigators to try and understand the causation of the incident."
Detective Chief Superintendent Trevor Lawry, head of policing for Bexley, Lewisham and Greenwich said: "Our thoughts are with the family of the deceased, who have suffered such an awful and devastating loss. We have officers in the location and I know these sentiments are shared by residents across the Bexley and London as a whole.
"Our inquiries are ongoing and we will continue to work with our colleagues in the London Fire Brigade to fully understand the cause of this terrible incident. In these very early stages we don't believe the cause of the fire is suspicious."