US fire crews who fought a huge warehouse blaze in sub-zero temperatures have described how the building represented a "big ice cube" as hose water froze on its exterior.
Images of the abandoned factory after the fire show an ice glaze covering the Chicago building which was gutted Tuesday's blaze.
The Chicago Sun-Times reports Fire Media Affairs Director Larry Langford described the warehouse fire as one of the worst he had seen.
"We haven’t had a fire this big in many years," Mr Langford told the newspaper.
The -12C temperature reportedly caused firefighters' uniforms to be covered in frost and ice as they worked at the scene.
Ice from freezing hose water covered the brick exterior of the the building as the inside continued to burn.
The fire reportedly jumped to a second building and was so extensive, more than 170 firefighters, a third of the city's total fire crew, was sent to battle the flames.
The roof and three walls of the warehouse collapsed during the fire which was contained in less than three hours.
“It’s turning into a big ice cube now,” Mr Langford said after the fire.
Officials reportedly do not know the cause of the fire which was reported by a firefighter who was driving past the building.