At least six people have been killed in a massive fire that engulfed a 24-storey apartment building in west London early Wednesday, meanwhile at least 50 people had been taken to hospitals, local police said.
London Fire Commissioner Dany Cotton told media that the cause of the fire is not known at this time.
Earlier reports said it is a 27-story building.
One side of the building totally blackened, with heavy smoke billowing into the air. Naked flames have been extinguished.
Xinhua correspondent at the scene said he could smell the burning smell as the police copter was hovering above.
London Mayor Sadiq Khan has declared the fire a "major incident."
A local resident who called herself Saha told local radio that she woke up at around 1:30 a.m. because of the sounds of sirens and people shouting for help.
"We came outside and we just saw that half of the building was in flames and it was slowly seeping up the other side and there were people signalling their lights on and off," she said.
The Grenfell Tower on the Lancaster West Estate, built in the 1970s and renovated several times, contains 120 homes.
It is feared many are trapped inside the blazing building as the fire broke out in early Wednesday.
Local reports cited witnesses as saying they saw people jumping from the building to escape the fire and they heard screams for help as well.
Other eyewitnesses said there are fears the residential building could collapse.
The London Ambulance Service said earlier it sent "a number of resources." Currently, there are 40 fire engines and 200 firefighters tackling the fire.
London Ambulances' hazardous environments team has also rushed to the scene.
The Metropolitan Police have closed major road A40 due to the fire and asked people to avoid the area so as to allow emergency services to get to the scene.
Police received report of the fire at the building at 1:16 a.m. local time (0016 GMT).
The Grenfell Action Group has posted an entry on its blog Wednesday morning, stating that it has previously raised concerns about fire safety at the tower block.
"Regular readers of this blog will know that we have posted numerous warnings in recent years about the very poor fire safety standards at Grenfell Tower and elsewhere in (the Royal Borough of Kensington and Chelsea)."
Although the cause of the fire is not yet clear, some residents have pointed to plastic cladding, which can be found on the ground, as "the problem."
Claims have also emerged online that residents at the tower block had warned last year of a fire risk of their building, which underwent a 10 million-pound refurbishment as part of a wider transformation of the estate last year.
An interviewee told the local radio that the fire started with the fourth floor but the smoke alarms had not gone off. Enditem