Skokie, IL – A dozen people were taken to hospitals after a malfunctioning furnace caused a carbon monoxide leak early Thursday at an apartment building in Skokie.

A resident of the building in the 8000 block of Keating Avenue called 911 shortly before 2:30 a.m. to report people feeling ill, and arriving police and firefighters realized it was a carbon monoxide leak, Skokie police said.

Twelve people, including several children, were evacuated from the building and taken to hospitals to be checked.

None was reported to be in serious condition, and all were expected to recover, according to the Skokie Fire Department, which said the leak was caused by a faulty gas furnace.