The five-alarm fire ignited at approximately 2 a.m. in the 2600-block of West Nelson Avenue in the Avondale neighborhood.
Fire officials said they believed the fire started on the top floor of the four-story brick warehouse, but flames spread to every floor of the building. Hours later, part of the building collapsed while ABC7 Chicago was on the scene.
Another one of the difficulties fire crews were facing were hot spots that would not die down. Fire officials said they were being forced to gather water from different sources to target those hot spots.
Fire crews conducted an initial search of the warehouse and did not find anyone inside. No reports of injuries were reported immediately, but officials said they could not confirm that no one was hurt until they had a chance to do a second check of the building.
A hazmat response was also called because of how big the structure is. However, a test of the water in the area was normal, officials said.
There was no word on what sparked the fire, which was causing authorities to block off portions of some surrounding streets, including Elston near Belmont.