Authorities have evacuated a West Virginia hotel after one guest was found dead and at least four others fell sick from suspected carbon monoxide exposure.

South Charleston fire Capt. Virgil White said firefighters detected high levels of the colorless, odorless gas on several floors Tuesday at the Holiday Inn Express. Later it was determined it came from a pool heater.

Fire Chief Greg Petry said four male victims, including the dead man, were found in one room on the fifth floor. The dead man had failed to show up for a meeting, and the others fell ill when they went to his room to check on him.

Authorities didn't know how many guests overall had been staying at the hotel.