A total of 58 people are presumed dead after this week's Grenfell Tower fire in London, police said Saturday.

"Based on what police now know, sadly 58 are missing and we assumed likely to have died," the Metropolitan Police Service said in an investigation update posted on its website. "The latest figure includes the 30 already confirmed to have died," it said.

Of 19 people treated at hospital, 10 are receiving critical care, according to police.

The search and rescue operation, made difficult by damage to the building caused by the fire, may take "many weeks to come," the post said.

The fire quickly spread through the residential tower in west London on Wednesday. Some experts have pointed to the type of exterior panels used in renovation work as a key factor behind the quick spread of the blaze.

Prime Minister Theresa May has been criticized for her handling of the situation and failure to meet residents of the tower when she visited the site Thursday.