Four people were taken to the hospital following a carbon monoxide leak at the Comfort Suites in Freeport.

According to CBS 13, Freeport’s fire chief said the hotel staff left a message Monday on the fire department’s business line instead of calling 911. He says he received the message Tuesday morning and went to the hotel on Route 1, which was then evacuated after he detected high carbon monoxide levels.

Two adults and one child had to be hospitalized, and the fire department later confirmed a fourth person was also brought to the hospital.

Investigators said the leak was caused by a malfunctioning water heater.