She visited the scene of the blaze on Thursday morning
Theresa May has ordered a full public inquiry into the Grenfell Tower fire disaster.
The Prime Minister said the inquiry, which is expected to cost several million pounds, was needed to ensure "this terrible tragedy is properly investigated".
Her decision comes as residents demand answers as to why fire swept through the 24-storey block in north Kensington so quickly, and why their warnings were apparently ignored.
Right now people want answers and that's why I am today ordering a full public inquiry into this disaster. pic.twitter.com/XTsH58zYqx— Theresa May (@theresa_may) June 15, 2017
The UK Government has come under criticism for not publishing a review into a fire in a tower block in Camberwell in 2009, the findings of which could have impacted on tower block safety.
The London mayor Sadiq Khan called for an inquiry and Labour leader Jeremy Corbyn said some "very hard questions have got to be asked and some very hard questions must be answered".
Mrs May visited the scene on Thursday morning, chatting to firefighters and emergency responders as she was shown the charred shell of the building where at least 17 people died.
Mrs May said: "We need to know what happened, we need to know an explanation.
"We owe that to the families, to the people who have lost loved ones and the homes in which they lived.
"That is why I am ordering a full public inquiry so that we can get to the answers, we can find out exactly what happened."
Britain's Prime Minister Theresa May arrives at Grenfield Tower in London
After his own visit to the site, Mr Corbyn said: "Hundreds of thousands of people in our country live in tower blocks, very high-rise tower blocks. Every single person who lives in a high-rise apartment today is going to be thinking, 'How safe am I?'"
It is not yet known what scope the inquiry will be, but Mrs May said it will be in addition to the immediate fire report and any potential police investigation.