BRATTLEBORO, Vt. (AP) — Fire officials in Vermont say six people have been treated for mild carbon monoxide poisoning after a boiler malfunctioned in an apartment building.

The Brattleboro Fire Department responded around midnight to the apartment building where a tenant reported that a carbon monoxide detector in the basement was going off. Firefighters found elevated levels of CO in the building and all 16 tenants were evacuated.

The fire chief says six tenants, including an infant, had high levels of CO in their blood. They were treated at Brattleboro Memorial Hospital.

The fire department says the alarm was sounding earlier in the afternoon but the detectors were either disconnected or ignored. The department is urging all residents to consider any alarm an emergency until the situation is deemed safe by trained professionals.

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