A major fire broke out in a London high-rise apartment building early Wednesday, leaving several people dead, many injured and others feared trapped inside. The apartment block on the Lancaster West estate in north Kensington, west London, has 24 storeys and 120 homes. The fire was reported shortly after 1 am local time.

The Metropolitan Police confirmed in a statement that a number of people have been killed in the fire. The police, however, said it will take some time to confirm the cause of the fire. London Ambulance Service said it had taken at least 50 people to the hospital.

London Fire Commissioner Dany Cotton said the fire fighters arrived at the spot within six minutes. She said there were a number of fatalities, but that she could not confirm the numbers because of the “complexity of the building”. “It would clearly be wrong for me to speculate further,” she said.

She said the fire at Grenfell Tower was an “unprecedented incident”. “In my 29 years of being a firefighters, I have never ever seen anything of this scale,” she said, according to The Guardian. “Crews wearing breathing apparatus and extended duration breathing apparatus have been working in extremely challenging and very difficult conditions to rescue people and bring this major fire under control.”

The fire safety advice issued to Grenfell Tower residents was to stay in their flats unless told otherwise, reported The Guardian.

Some residents say they were offered a similar advise of staying put in their apartments in the event of a fire breaking out back in 2014, reported The Guardian. A newsletter to residents published in 2014 said:

“Our longstanding ‘stay put’ policy stays in force until you are told otherwise. This means that (unless there is a fire in your flat or in the hallway outside your flat) you should stay inside your flat. This is because Grenfell was designed according to rigorous fire safety standards. Also, the new front doors for each flat can withstand a fire for up to 30 minutes, which gives plenty of time for the fire brigade to arrive.”

Sadiq Khan, the Mayor of London, said questions need to be answered about the fire advice. Speaking to a radion station, he said, “Thankfully residents didn’t stay in their flats and fled to safety. One of the concerns that we have is it’s a 24-storey building but for obvious reasons, with the scale of the fire, our experts weren’t able to reach all the way to the top, so of course these are questions that need to be answered as soon as possible.”

He said the advice would be looked into, reported the BBC. “Across London we’ve 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 it’s been alleged, of tower blocks not being properly serviced and maintained,” he added.

Meanwhile, Rydon, the company responsible for cladding and retrofitting refurbishments at Grenfell Tower have removed all references to the refurbishment from their website, reported The Guardian.

Around 250 firefighters, 40 fire engines, 100 medics and 100 Metropolitan Police officials are at the spot and trying to evacuate residents from the tower as well as those from buildings nearby. Several people have sustained injuries, the police said, and are being treated.

The whole building is ablaze, and there are fears that it might collapse. Falling, flaming debris is making firefighting especially difficult. Eyewitnesses claimed many had been signalling from inside the building, indicating that they could not get out.

The London Fire Brigade released a statement on Facebook:

Forty fire engines and over 200 firefighters and officers have been called to a tower block fire on the Lancaster West estate in north Kensington this morning. The brigade has received multiple calls. The fire is from the second floor to the top floor of the 27-floor building.

Assistant Commissioner Dan Daly said: “Firefighters wearing breathing apparatus are working extremely hard in very difficult conditions to tackle this fire. This is a large and very serious incident and we have deployed numerous resources and specialist appliances.“

The brigade was called at 0054 and is still at the scene. Fire crews from North Kensington, Kensington, Hammersmith and Paddington and from surrounding fire stations are in attendance. The cause of the fire is not known at this stage.

London Mayor Sadiq Khan tweeted:

The NHS ambulance services are at the scene.