HELENA, Mont. (AP) — Five people were hospitalized after being exposed to carbon monoxide at a Helena hotel, fire officials said.

A guest called 911 Thursday evening after their child became ill, Jorgenson’s general manager Ann Marie Bowers tells the Independent Record.

Responding firefighters knew what was wrong based on the people’s flu-like symptoms, flushed skin and lethargy, said Fire Marshal Lou Antonick.

The hotel and an adjacent apartment complex were searched and ventilated.

The leak was traced to an issue with the ventilation of the exhaust from the heating system for the hotel’s swimming pool, firefighters said Friday. The pool heaters and the natural gas were shut off until repairs could be made.

The five people were hospitalized overnight and were released early Friday afternoon, said St. Peter’s Health spokeswoman Katie Gallagher.

Antonick said fire crews did not find any carbon monoxide detectors, which are required in commercial buildings.

The hotel installed plug-in carbon monoxide detectors after a fire inspection last year, Bowers said, and didn’t realize they had been stolen until Thursday night. She said the hotel would install hard-wired carbon monoxide detectors.

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