The blaze destroyed a two-storey flat and damaged the one above on Lewisham Road just before midnight on July 8.
A boy, named by his family as Fabian Henry, died at the scene.
A neighbour told The Mirror: “We first heard people running and screaming around midnight, and then there was a series of loud noises that sounded like gunshots, followed by glass shattering.
“It seems those were the noises of the fire damage. Firefighters and police arrived quickly.”
Fabian’s family have paid tribute to the “talented” footballer.
LIVE updates as boy, 12, dies after fire rips through flats in Lewisham
His aunt Suezette Edwards told Metro that Fabian was a big Manchester United fan who was “very good” at football.
She said: “He was a big Manchester United fan. His father had died from cancer. He was lovely.
“The family wanted him to be a doctor. He was also very good at football. We are all heartbroken.”
The schoolboy’s former primary school teacher, who was also the scene, said that he had a “great” heart.
He added: “He was always the captain always up for everything. He was a talented footballer he could play any position. I taught him for seven years at primary.
Heartbreaking tributes to ‘talented’ footballer, 12, who died in Lewisham flat fire
“When he sees me he still gives me a big hug and says he scored yesterday. He was a pleasure to teach. I wish all kids were like him”.
The dad of his best friend who visited the scene also told Metro that his son and Fabian were on a school trip yesterday.
“They were going to meet up and play football today”, he added.
He continued: “The boy lost his father recently.
“My son only just found out about it on the way to school and he turned round and came home.
“He was too upset to go, he’s gutted.
“The boy was lovely my son has lost his best friend.”
A 54-year-old woman was injured and treated at the scene by the London Ambulance Service while three others left the block before the Brigade arrived.
Lewisham Road is closed between Penrose Way and Lewisham Hill.
The cause of the fire is not thought to be suspicious and is being investigated by the London Fire Brigade and Metropolitan Police.
Detective Chief Inspector Danian Reid, from the Met’s local investigations team in south east London, said: “This is a 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.
“We understand the impact this will have on the community and there will be local neighbourhood officers, and other emergency services, in the area as enquiries continue.”
A London Fire Brigade spokesperson said: “Ten fire engines and around 70 firefighters tackled a fire at a block of maisonettes on Lewisham Road, Lewisham.
“A maisonette split between the ground and first floors was destroyed by the fire.
“Part of a maisonette split between the second and third floors was damaged by the fire along with a small part of the external fascia of the building.
“One woman was treated on scene by London Ambulance Service.
“Three further people left the building before the Brigade arrived.
“Control Officers took the first of 14 calls at 2355 and mobilised crews to the scene from Greenwich, Lewisham, Lee Green and surrounding fire stations.
“The fire was under control by 0202.
“The cause of the fire is under investigation.”
A London Ambulance Service spokesperson said: “We were called at 11.56pm on Tuesday 8 July to reports of a fire in Lewisham Road, SE13.
“We sent a number of resources to the scene including ambulance crews, advanced paramedic practitioners, an incident response officer and members of our Hazardous Area Response Team (HART).
“We treated one person who was discharged. Sadly, a boy was pronounced dead at the scene.”
