But Jonathan Stone, a safety manager at the Hammersmith and Fulham Council, which owns and runs the building, said precautionary measures taken by the local authorities had "prevented another Grenfell".
Both Mr Stone and the Labour council's leader Stephen Cowan, who were at the scene after the fire, told PA they had been advised that the fire alarms had gone off as expected.
The council has a system called Fire Safety Plus which has taken steps including installing fire safety doors to help residents stay protected.
The fire was brought under control by around 10.55am, which Mr Cowan said was partly made possible by the lack of flammable cladding - a crucial difference from the Grenfell Tower.
He told PA residents may understandably be "in shock" after the ordeal and that reports of fire alarms failing to sound were understood to be inaccurate.
Labour MP for Hammersmith Andy Slaughter told PA at the scene that work he understood the fire would be "of great concern" and said a full report would be completed to formally establish the cause.
"Any fire, particularly in high rise buildings, is going to be of great concern to residents and they will need reassurance that all safety measures are in place," he said.
Mr Shakat recalled watching the Grenfell Tower blaze from the same flat that caught fire on Tuesday, saying the blaze brought memories of the tragedy back.
He said: "I remember seeing it. We were playing Playstation."
He added: "I thought I was going to die today."
Detailing how the events of the morning unfolded, he said: "He (Mr Mohamed) forces me to wake up. I follow him. I went into the room and the whole room is on fire. I ran to the sink, I got a bucket of water and I tried to discourage the fire and then it got worse.
"I was in shock," he said. "I didn't know what to do."
London Ambulance Service said two ambulances and a Hazardous Area Response Team attended, with one person taken to hospital and two assessed at the scene.
In a statement from the scene, station commander David Bracewell said: "Firefighters dealt with a fire on the 12th floor of a tower block in W11. Three people from the affected flat left before the brigade arrived. A number of other residents evacuated the building.
"Firefighters led six residents to safety via an internal staircase. Further residents who were not affected by fire, heat or smoke were advised to remain in their flats.
"In the early stages we used new technology called 9Eye that enabled a caller to send live stream videos of the incident straight into the brigade's 999 call centre.
"We've also used a 32m turntable ladder to put water on the outside of the building."
Kensington and Chelsea council leader Elizabeth Campbell said the incident may have brought back "awful memories" of the Grenfell tragedy.
She said: "We are also acutely aware of the awful memories and trauma these events can bring back to the community, and we have asked colleagues in the NHS and CNWL to ensure that support is clearly signposted."
