Two residents of a South Kohala home were treated for exhaust fumes Sunday after a malfunctioning pool heater rendered them unconscious, the Hawaii County Fire Department said.

Firefighters responded to an 11:09 a.m. alarm to a two-story house in the Mauna Kea Fairways residential development, the fire department said. They found two unresponsive people inside and took them out of the house.

Officials said a possible malfunction of the pool heater’s exhaust sytem may have caused the problem. The house has a pool outside the living room. The residents were treated and allowed to return home.