The incident happened around 1:10 a.m. at the Intercontinental Hotel on Michigan Avenue, the Chicago Tribune reported.
Someone reported that the victim, identified as Nicholas Wieme, was threatening to jump from the roof.
When rescue crews arrived, they learned Wieme had fallen down the smokestack, said Fire Department spokeswoman Meg Ahlheim. Wieme had fallen 22 feet down a 6-foot wide smokestack and became wedged where the chute angled before dropping 42 floors, Ahlheim said.
About 125 firefighters and paramedics were called to the scene for a "confined space rescue," Ahlheim said.
"We had to send members from the top down on ropes to assess his condition. The whole time we're monitoring the situation for toxic gases," said Special Operations Chief Michael Fox. "We found the best way to get out him was to go about two floors below, and we had to cut the duct work for the chimney, which was made out of steel. And eventually we ended up sliding the victim down into the hole and removing him from the building."
It took crews about four hours to get Weime out.
Early on in the rescue effort, Weime was texting his girlfriend, but firefighters lost contact with him around 3:15 a.m., the Minneapolis Star Tribune reported.
Raymond Vermolen, general manager of the hotel, released a statement saying Intercontinental "holds the safety, comfort and well-being of our guests and employees as our top priority and concern. Our thoughts and prayers are with the family and friends of the guest at this difficult time. The hotel staff will continue to cooperate fully with authorities in their investigation. All further questions should be directed to the Chicago Police Department."
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