Canonsburg, PA – A 20-year-old Canonsburg resident was found dead of carbon monoxide poisoning in his apartment Monday morning.

Canonsburg police responded to the basement apartment at 220 Grace Ave., about 7:30 a.m., to check on a man who had not been heard from in a couple of days. Police found the man lying in the bedroom, dead, according to police Chief Alex Coghill. The man’s name has not been released, as authorities have not yet notified his next of kin.

Coghill said police and Canonsburg fire officials then checked the street-level apartment in the building.

“There was an elderly woman living there and she also had carbon monoxide poisoning,” Coghill said.

Fire Chief Tim Solobay said the woman was complaining of a headache and was transported to a Pittsburgh hospital. A woman who lives in the second-story apartment had just left the home to take her two young children to school, Coghill said. She was contacted and told to go to a nearby emergency room.The woman and children were all treated for carbon monoxide poisoning.

“The scariest thing is how catastrophic it could have been,” Coghill said. “We could have been looking at multiple victims if it had gone on longer.”

The apartment complex is owned by Gus Mantalis, who lives nearby, Solobay said.

Coghill said the symptoms of carbon monoxide poisoning are lethargy, headaches and nausea, which can often be confused with other illnesses. Solobay said the building had a reading of more than 400 parts per million of carbon monoxide.

“Once you get over 200 parts per million, you have to use a respirator,” he said.

Solobay said the 20-year-old man had taken the batteries out of his carbon monoxide detector, though his smoke alarms were working. Solobay said the CO detector in the second-story apartment was going off when they arrived, but there was no CO detector in the older woman’s apartment.

“We strongly advise folks to always have good smoke and CO detectors and to check the batteries on them,” Solobay said.

Solobay advised that people not ignore smoke or CO detectors and to call the fire department if they have any issues with them.

“We have them to give away,” Solobay said. “We’d rather come out and help you get the detectors working again, rather than respond to the worst-case scenario, which unfortunately happened this morning.”

The fire department has responded to an unusually high number of carbon monoxide calls so far this year. Solobay said that’s largely due to people starting their furnaces without having themchecked first.