UPDATED 10.20pm

What we know

• Huge fire has engulfed a West London tower block, Grenfell Tower in Latimer Rd
• Six people have been confirmed dead
• At least 50 patients have been taken to hospital
• The cause of the fire is being investigated
• 200 firefighters with 40 engines are at the scene
• The tower has at least 27 storeys and contains 120 flats
• Streets around the building have been cordoned off
• London mayor Sadiq Khan declared blaze as a "major incident"

London Fire has engulfed a 24-storey block of flats in west London, killing at least six people, injuring at least 50 more and trapping some residents asleep inside the towering inferno.

Flames licked up the sides of Grenfell Tower in North Kensington as 200 firefighters, backed up by 40 fire engines, fought the blaze for hours early Wednesday.

London Fire Brigade said the fire engulfed all floors from the second to the top of the block, where several hundred people lived and contained 130 apartments.

"In my 29 years of being a firefighter, I have never ever seen anything of this scale," London Fire Brigade Commissioner Dany Cotton told reporters.

"I am very sad to confirm that there have been a number of fatalities, I cannot confirm the number at this time due to the size and complexity of this building."

London Ambulance Service said more than 50 people had been taken to hospital.

A nearby resident Jody Martin told Newstalk ZB he ran into the building to warn people about the fire.

"I grabbed an axe out of the back and ran around the building looking for a fire exit, screaming at the building - I couldn't see a fire exit at all."

Martin said the building's now a burnt out husk, and he thinks everyone from the fourth floor up is dead.

MORE: Eyewitness describes London inferno: 'There's nothing left'

Pictures from the scene showed flames engulfing the block and a plume of smoke visible across London, while others showed residents looking out of windows in the block.

Residents related how they woke up to the smell of burning and rushed to escape through smoke-filled corridors.

Nassima Boutrig, who lives opposite the building, said she was awakened by sirens and smoke so thick that it filled her home as well.

"We saw the people screaming," she said. "A lot of people said 'Help, help, help.' The fire brigade could only help downstairs. It was fire up, up, up. They couldn't stop the fire."

The smell of it. Fire now covers all windows where people were. #grenfelltower #london pic.twitter.com/4Dp7LnGDGR

— Fabio Bebber (@biobber) June 14, 2017

London Fire Brigade Assistant Commissioner Dan Daly said firefighters wearing breathing apparatus were "working extremely hard in very difficult conditions to tackle this fire".

More than 20 ambulance crews were at the scene.

London Mayor Sadiq Khan said a "major incident" had been declared and questions will need to be answered over the safety of tower blocks.

"Across London we have many, many tower blocks and what we can't have is a situation where people's safety is put at risk because of bad advice being given or if it is the case, as has been alleged, of tower blocks not being properly serviced or maintained," he told BBC radio.

MORE: Burning London tower 'too hot' for emergency services to enter

Police closed the A40, a major road leading out of west London, while some parts London's underground train network were closed as a precaution.

The cause of the fire, which broke out just before 1am local time, is not known, the Fire Brigade said. Residents said repairs, including the addition of some sort of cladding, had been made to the exterior of the block recently.

Sleepless night for West London, I see people waving from inside the building. #GrenfellTower #latimerroad pic.twitter.com/KtedXMLcFa

— Julia (@julia_spain) June 14, 2017