Chicago, IL  – Chicago Fire Department responded to an apartment containing potentially deadly high carbon monoxide levels near Douglass Park Thursday morning.

Fire officials said the CO level reached 490 parts per million (PPM) due to a bad vent on a furnace inside a multi-flat building, in the 1200 block of South California Avenue.

Two people were transported to Mt. Sinai Hospital in unknown condition – nine others refused treatment.

There were no carbon monoxide detectors inside the building, fire officials said.

They are urging residents to get and use both carbon monoxide and smoke detectors.