Carbon monoxide sickens 12, shutters Berks County middle school

A Berks County school has been shuttered after 12 people were sickened there by carbon monoxide.

Fleetwood Area Schools Superintendent Greg Miller says a community theater group was practicing for a play in the district's middle school when group members started getting sick around 8:30 p.m. Thursday.

Twelve people were treated at hospitals and are expected to recover. Authorities eventually determined that carbon monoxide caused the problems, and classes there were canceled Friday as a precaution.

The rest of the districts' schools were not affected.

Investigators are still trying to determine what caused the carbon monoxide issues.

The Associated Press contributed to this report.