Elevated levels of carbon monoxide levels forced the evacuation of Earl Prentice public school in Marmora Wednesday morning.
Hastings and Prince Edward School Board spokeswoman Kerry Donnell confirmed the principal smelled natural gas while the children were outside during recess and called the fire department.
Fire crews arrived at the school at 17 Williams Street around 1:45 p.m. to find an elevated level of carbon monoxide.
Students are now at Marmora Senior school. Dismissal is at 3:40 p.m.
Donnell says if parents want to pick up their children early they are welcome to do that.
She added that maintenance crews are working on the issue and classes will resume as usual Thursday.