Firefighters were called to the Sanderford Road Learning Center just after 9 a.m. They said it appeared a stove was left on - causing gas to build up all night.
About 60 kids and six adults were exposed to the gas. The school was evacuated and paramedics checked over students and staffers at the scene. There were no reports of anyone going to the hospital.
The daycare was expected to reopen later Thursday morning.