Rescue operations are on to save persons trapped in a tower of blocks in west London that went up in flames on Wednesday, but Mayor Sadiq Khan wants answers to questions that the situation has raised.

Six deaths have been recorded and at least 74 persons were injured.

Twenty persons are receiving critical care.

Police have described the situation as shocking, but Khan said questions will need to be answered over the safety of tower blocks.

It is a 24-storey building and some residents said they had been advised they should stay in their flats in the event of a fire, while the block’s residents’ association had previously warned it was worried about the risks involved.

“These questions are really important questions that need to be answered,” Khan told BBC Radio.

“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.”

Police told reporters on Wednesday that investigations which are still in early stage would be complex and thorough.

Fire engulfed a 24-storey block of 130 apartments in central London.

Many are still trapped because the fire started while they were still asleep inside the towering inferno.

Flames licked up the sides of the block in the north Kensington area as 200 firefighters, backed up by 40 fire engines, fought the blaze for hours.

Plumes of black and grey smoke billowed high into the air over the British capital hours after the blaze broke out at the Grenfell Tower where several hundred people live.