Emergency crews were on the scene at an apartment building in the 8000 block of Keating in Skokie. A resident of the building called 911 around 2:45 a.m. Thursday after feeling ill.
Firefighters were forced to break into some apartments to help residents get outside to safety. When police and fire officials arrived, they realized that a carbon monoxide leak had occurred, police said.
The victims were brought outside by emergency officials and given oxygen. There have been no life-threatening injuries reported. It's not yet known what caused the high levels of carbon monoxide in the building.