A suspected carbon monoxide leak forced the evacuation on a theater in Park Falls, while about 30 people had to be treated for carbon monoxide poisoning.
Authorities were called to the Park Theatre at about 9:45 pm on Monday for a report of a woman having a seizure. Another woman reportedly fainted when they arrived, prompting concerns about a carbon monoxide leak.
Fire department officials confirmed high levels of the poisonous gas, although it was not clear if the source was a furnace or water heater in the building. The appliances are scheduled to be inspected Tuesday.
About 20 people were transported an area hospital for treatment. All of those exposed to the gas are expected to recover quickly.
UPDATE: Police on Tuesday increased the number of people sickened by the leak from 20 to 30.