Des Moines, IA – Police say more than 30 children and teenagers were taken to hospitals after being sickened by carbon monoxide during a church choir rehearsal in Iowa.

Des Moines Police Capt. Dave Huberty says a generator was being used Sunday to power the Lord Revival Center Church of God in Christ. He says the fumes flowed back into the building as the children and teens practiced for about three hours.

Huberty told The Des Moines Register that no serious symptoms had been reported by late Sunday.

Huberty said it was accidental and fire crews ventilated the building.

Carbon monoxide is an odorless and colorless gas that can cause headaches, nausea, dizziness and other symptoms. Inhaling high levels can cause death.