As rescue effort continues, death toll up to 17 from London high-rise fire Authorities admitted it was unlikely that any more survivors would be found.

 -- Rescue workers continued to search for survivors on Thursday, a day after a fire swept through a London high-rise, but officials admitted it would be a "miracle" if more people are found alive as the death toll rose to 17.

"Tragically now we are not expecting to find anyone else alive," London Fire Commissioner Dany Cotton told Sky News early Thursday. "The severity and the heat of the fire will mean that it will be an absolute miracle for anyone to be left alive."

As the search operations continued, authorities braced for the death toll to increase. In addition to those killed, nearly 80 people were injured at the inferno, at Grenfell Tower in North Kensington, which erupted early Wednesday. Of those, 18 were listed in critical condition.

"Due to the severity of the fire and the way things are, it will take a long time for us to be able to do that search to properly identify anyone who is left in the building, but we will do that as soon as we can in conjunction with the police," Cotton said. "There are, as we believe, still unknown numbers of people in the building."

Cotton commended rescue workers for doing "absolutely sterling work" and said her team hopes to conduct a fingertip search of the building once its edges are deemed secure.

The fire reportedly started at around 1 a.m. local time Wednesday on the fourth floor of the 24-story residential building. The cause of the fire is still unknown, but U.K. Prime Minister Theresa May, who visited the still smoldering wreckage on Thursday morning, promised a "proper investigation."

Some tenants previously complained about the upkeep of the tower, specifically warning about the fire risk. In November a residents' group, Grenfell Action Group, said that only a "catastrophic event" would expose the concerns it had about the building's landlord, according to a blog post from the group.

It was not clear exactly how many residents were in the building, but the tower, built in 1974, contained 120 apartments, according to its management company, the Kensington and Chelsea Tenant Management Organisation.

Family and friends of residents posted missing person bulletins throughout the North London area, and others shared images of loved ones who are unaccounted for.

London Ambulance Service said that as of Thursday morning, 68 people had been taken to local hospitals and another 10 people had self-reported and been accounted for. Other survivors have been asked to report at the Portobello Rugby Club in London and "make themselves known."

Fire officials said it took nearly two hours to gain control of the massive fire. The London Fire Brigade dispatched at least 40 fire engines, 20 ambulance crews and more than 200 firefighters in an effort to battle the conflagration.