Manchester, CT – Seven people were treated for carbon monoxide poisoning after a furnace malfunctioned at a Manchester duplex this morning, fire officials said.

Firefighters responded to 130 and 132 Hilliard Street in Manchester around 7 a.m. Friday. When they arrived, Manchester police were already on scene helping two children and one adult woman out of the home at street number 130.

Four people form 130 Hilliard Street were taken to Manchester Memorial Hospital for CO poisoning. From there, they were transferred to Hartford Hospital, where they were treated in the hospital’s hyperbaric oxygen chamber, fire officials said.

Investigators found that CO gas had leaked from a malfunctioning furnace and spread throughout the duplex. Initial tests revealed extremely high levels of CO. Although the three residents of 132 Hilliard Street next door did not show any signs of CO poisoning, they were taken to the hospital as a precaution.

Less than an hour later, around 8 a.m., officials responded to another CO incident involving an oil furnace at 41 Santina Drive. Fire officials found the furnace in a state of disrepair and took a female resident to the hospital for an evaluation. Firefighters said she was exposed to triple-digit levels of CO.

Fire officials said these were the first two serious CO calls of the season.

To protect against CO poisoning, officials emphasize the importance of installing CO detectors and having your heat sources checked at the beginning of the season