The firefighter, whose name was not released, was experiencing shortness of breath after returning to his firehouse Sunday night, the Chicago Tribune reported.
He was taken to the Little Company of Mary Hospital where he went into cardiac arrest, officials said. He was pronounced dead at 11:21 p.m.
Officials said he had been a firefighter for 18 years.
The death came three days after the funeral of Capt. Herbert Johnson, a 32-year fire department veteran who died while fighting a fire.
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