Nearly 50 people who attended a Church of Jesus Christ of Latter-day Saints meetinghouse in Utah were treated for carbon monoxide poisoning, church officials said Monday.

Fifty-four people who attended the meetinghouse in Monroe, roughly 174 miles south of Salt Lake City, reported symptoms, and 49 were treated for elevated levels of the poisonous gas, the church said in a statement.

The statement blamed the incident on a malfunction with the building’s heating system and said church officials closed the meetinghouse until they could ensure its safety.