Another neighbour said she was “stunned by the devastation” of the blaze.
“This will leave a devastating impact. I just feel numb,” the 60-year-old added.
Another resident, who did not wish to be named, said: “It’s a very distressing time for us and the neighbourhood.
“We’ve all grown up together. We’ve all lived in these houses for 25, 30 years. Everyone knows everyone.
“It was a very big fire. The fire was blazing. It was non-stop. It’s a very tragic time.”
In a statement, the London Fire Brigade (LFB) said: “A woman and a child were rescued from the second floor of one property by crews wearing breathing apparatus and received immediate emergency care.
“Both were sadly declared deceased at the scene by a Helicopter Emergency Services (HEMS) team.
“Two more children were discovered inside the property as crews carried out firefighting operations and were declared deceased at the scene.”
Supt Allen, from the Met’s local policing team in north-west London, said: “This is an extremely tragic incident and our thoughts are with everyone involved… we continue to work alongside investigators from the London Fire Brigade to establish the cause of the fire.”