Fire crews were still at the scene this morning following last night’s blaze, which is thought to have caused massive damage to the structure - it is understood large parts of the roof have collapsed.
Roads leading into City Square have been closed, causing gridlock on most major routes into the city.
At its height there were three aerial appliances, four large jets and seven other pumps fighting the fire.
Sean O’Flynn, white watch commander from Hunslet Station who was one of the first on the scene said the fire had spread into a void between a false ceiling and the roof, eventually causing the collapse, adding: “When the roof collapsed, we had to ensure everyone was out and that made it difficult to fight the fire inside.”
He said they had to work hard to ensure the blaze did not spread to adjacent buildings.
Fire investigation crews will today begin the task of trying to find the cause of the fire, alongside police scene of crime officers.