Seven trailers on the loading dock caught fire, but no one was injured, UPS spokesman Mike Johl said.
The fire never spread to the 1.5-million-square-foot Chicago Area Consolidation Hub, which employs 8,000 workers and handles 2 million packages a day during the holiday season, Johl said.
The company estimated fewer than 2,000 packages were damaged or destroyed, most of them bound for Denver, New Jersey and DeKalb, Ill.
``UPS is contacting the customers whose packages were affected so that alternative arrangements can be made, and we are sincerely apologizing for the inconvenience,'' UPS said.
Normal operations had resumed by midday.
The cause of the fire was under investigation.
Atlanta-based UPS has estimated that one in every 10 packages it delivers worldwide between Thanksgiving and Christmas passes through the center in Hodgkins, 10 miles outside Chicago.
