The Chicago Fire Department was investigating a carbon monoxide leak Thursday morning in a Chinatown apartment building.
Shortly after 5 a.m., firefighters were going door-to-door in the approximately 100 units in the seven-story building in the 2200 block of South Princeton, trying to confirm the source of the high carbon monoxide reading, fire officials said.
Peak carbon monoxide readings were reported at 130 parts per million and a Level 2 HazMat response was called, fire officials said.
Fire officials said the leak may have happened because of a new heating unit.
As of 5:18 a.m., no one had been evacuated and no one was taken to the hospital. All heating in the unit had been shut down.