BARRIE -- Students at St. Monica's Catholic School on Steel Street in Barrie were evacuated on their first day back following the winter break.
School officials say "unacceptable levels of carbon monoxide" were detected from a heating unit on the rooftop after some at the school reported "feeling odd" on Monday morning.
Those reports prompted school officials to move the 350 students and 40 staff members from the building on Monday.
Staff and students were bused to St. Joseph's high school. St. Monica's was closed for the remainder of the day for fire and Enbridge Gas crews to check into the situation.
St. Monica's posted an update on its website stating, "Emergency services investigated and deemed the levels safe."
Everyone was cleared to head back, but school officials decided to continue to air out the building and said it would be open as usual on Tuesday.
Barrie Fire tells CTV News that paramedics checked several people as a precaution and two students were taken to hospital, again as a precautionary measure.
