The Waterloo Region District School Board closed the public school in Floradale Tuesday morning after a carbon monoxide scare.
School buses carrying students to Floradale Public School were diverted after noxious fumes were detected in the school.
Firefighters were called after two teachers started to become ill.
Entering the building before students arrived for the day, with equipment designed to detect carbon monoxide, they detected positive readings.
When buses began to arrive at the school, they were directed to the Floradale Mennonite Church parking lot across the street.
School officials began the task of contacting parents of the children.
Heating units on the roof, determined to be the most likely source of the pollutants, were turned off as firefighters went room by room, ventilating each room until safe readings were reached.
Waterloo Region District School Board employees are looking at the heating units in the attempt to find the problem.
The school is expected to reopen Wednesday.
