Two teenagers have been arrested after hundreds were evacuated as a large blaze erupted at a block of flats in Hertfordshire on Tuesday morning.
Firefighters were called to 16-storey Abbey View in Garsmouth Way, Watford around 5am.
It is believed an outside bin was set alight and flames spread to the nearby building.
Hertfordshire Police and the East of England Ambulance Service are also in attendance at the Meriden estate, where world heavyweight boxer champion Anthony Joshua, 32, grew up.
Two boys, aged 13 and 14, have been arrested in connection with the investigation and remain in police custody at this time.
Eyewitness Andrew Carberry ran from his flat shouting “fire” to alert neighbours, and told the Standard: “My only hope was to save lives. I didn’t want another Grenfell.”
Emergency services said there had been no reports of casualties at this time. One person was treated for smoke inhalation.
Mr Carberry added: “I was in the front room of my flat when I heard what sounded like an explosion.
“I then leant out the window and could hear the fire.
“I got dressed, went downstairs and walked down road. I shouted fire 20 times to alert the people in the tower block.
“By that time, the fire brigade arrived. It looked like it started at the bottom of the flat.
“The worst damage was the bottom few floors. One family got out saying they heard my shouts of fire, which was good.”
Hertfordshire Police said: “We were called at 4.50am today to reports of a fire at a block of flats in Garsmouth Way, Watford.
“Officers attended to assist colleagues from Hertfordshire Fire and Rescue Service at the scene. The East of England Ambulance Service also attended and road closures were in place.
“Residents of the block were evacuated while the fire, which started in a bin store, was put out.
“Minor smoke inhalation-type injuries were reported. The cause of the fire is being investigated.
“Two males, aged 13 and 14, have been arrested in connection with the investigation and remain in police custody at this time.”
Herts Fire and Rescue said: “We were called to reports of a fire in a bin store at a residential building in Garsmouth Way, Watford at around 5am this morning.
“Eight fire engines are on the scene and fire fighters evacuated floors one to four.
“Other emergency service colleagues are also in attendance. We can confirm that the fire has been put out and there were 10 pumps.”
The ambulance service added: “We currently have multiple resources at a fire at flats in Garsmouth Way, including our Hazardous Area Response Team.
“As of 06.11am, other than one person treated on-scene for smoke inhalation, there have been no casualties and no-one has been transported to hospital.
“The incident is still live however, and crews are still assessing residents that have been evacuated.”
Anyone with information is asked to contact Hertfordshire Police on 101, quoting ISR 90 of 12 July, 2022.