Chicago, IL- A carbon monoxide leak Wednesday evening led to the evacuation of a high-rise YMCA building in downtown Chicago, Chicago Fire Department officials said.

The leak was reported about 7:30 p.m. at the Lawson House YMCA, 30 W. Chicago Ave., authorities said. All occupants in the 20-story building evacuated on their own, fire Cmdr. Will Knight said. No injuries were reported.

Fire personnel detected elevated readings of carbon monoxide in the building, Knight said.

Based on a preliminary investigation, a faulty boiler or furnace may have triggered the leak, Peoples Energy spokeswoman Elizabeth Castro said.