A top firefighting official in London said that there are still “unknown numbers of people” inside London’s Grenfell Tower apartment complex, the building engulfed by a huge fire on Wednesday morning, leaving at least 17 dead.

According to The Guardian, firefighters worked through the night to put out the last of the flames, but police said that the death toll was likely to rise.

Speaking to Sky News, London Fire Commissioner Dany Cotton said that the likelihood of firefighters finding anyone else alive at the scene was low.

"Tragically, we are not expecting to find anyone else alive. The severity and the heat of the fire will mean that it would be an absolute miracle for anyone to be left alive," she said.

Cotton said that, due to the “severity of the fire,” it will take a "long time" to search the tower "to properly identify anyone who is left in the building.”

According to The Telegraph, some 600 people were believed to have been inside the building before the blaze began.