Two National Cleaners and Laundry workers and a police officer became ill after they were exposed to high levels of carbon monoxide, according to a Lockport Township fire news release.
The heating system at the store on North Larkin Avenue in Crest Hill had an issue that created high levels of carbon monoxide, Lockport fire officials said.
Three people were taken to nearby hospitals. Two store employees fell ill and a Crest Hill police officer who responded to the scene also become ill after entering the building.
About noon, firefighters received a call about a possible gas leak inside of National Cleaners and Laundry, Lockport Township Deputy Fire Chief Frank Blaskey said.
Investigators determined it was not a gas leak.