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CANONSBURG (KDKA) — One person has died and four others were hospitalized due to a case of suspected carbon monoxide poisoning in Washington County.

Firefighters were called to a home divided into three apartments along Grace Street on Monday morning.

(Photo Credit: KDKA Photojournalist Lori Sperling

Officials say the carbon monoxide levels in the building were high enough that firefighters had to wear their masks inside.

Crews were able to get two women and two children out, but found a man dead in the bedroom of his basement apartment.

“Unfortunately, we found him in his bedroom, and levels again were exceeding 400 parts per million. We immediately started ventilating the building, turning off the gas at the meter and trying to evaluate and making sure the rest of the people in the house could be accounted for,” said Canonsburg Fire Chief Tim Solobay.

The victim has been identified as 20-year-old Brendan K. Downey, of Canonsburg.

Officials say Downey had a carbon monoxide detector in his apartment, but the batteries were missing.

The women and children were taken to the hospital. Their conditions have not been released.

It’s believed a faulty furnace may be to blame, but officials are still investigating the source.

This is the third carbon monoxide emergency in Canonsburg in three weeks.