Chopper7 was over the scene at Access, a secure document storage facility, in the 1200 block of Humbracht Circle just after 4 p.m.
Officials said the warehouse was stacked floor to ceiling with boxes of documents, providing ample fuel for the fire.
What workers said began as a few boxes on fire grew into an inferno.
"These walls are collapsing on us," said Bartlett Fire Chief William Gabrenya. "We don't want to get any of the firefighters within that collapse zone, so at this point we're all aerials operations."
The smoke from the fire was so intense the plume was visible on ABC7's Live Doppler 7 Max weather radar.
The trouble began around 10 a.m. Officials said a sprinkler system initially kept the fire in check, but when a series of steel racks being used to store boxes collapsed, there was no saving the warehouse.
In a statement, Access said all its employees evacuated the building and are safe. The company added that it is working with local authorities to determine the cause of the fire.
Access also said a recovery team is working onsite to "assess the situation, determine any impact, and take necessary actions."
And while nearly 10 miles southwest of the fire a resident in Geneva sent ABC7 a photo of possible ash from the blaze he found in his yard, officials said the air is safe.
"It's just paper products that are burning in there, so we're not really concerned with air quality at this point," Gabrenya said.
The Village of Bartlett said the following roads are closed in the area as crews battle the fire: Munger Road between W. Bartlett Rd. and Stearns, Brewster Creek between Spitzker Rd. and Munger, N. Humbracht Circle closed at Munger Rd.
The cause of the fire is still undetermined. Calls made to Access by ABC7 were not returned.