The incident was reported at around 11:46 a.m.
According to Chief Bill Cairns of the Lima Fire Company in Middletown Township, the initial report was of a diesel leak inside the JC Penney store.
Once firefighters arrived, Cairns says, they found a high reading of CO.
Cairns says the ventilation system was malfunctioning and would not turn off.
"Which took CO throughout the entire mall; we wound up shutting the entire mall down," Cairns said.
The JC Penney store will stay closed for the day due to the fuel leak in the heater room.
No injuries were reported.
