Emergency services were called to the site, where they found the children complaining of headaches, dizziness and difficultly breathing.
Seven of the children — all between the ages of five and eight — were transported by ambulance as a precaution.
None of the children lost consciousness and their lives are not in danger, according to Sgt. Pierre Tremblay with the Richelieu-Saint-Laurent police.
The pool is currently closed and emergency officials say they have not yet determined what made the children sick .
Investigators think the problem was centred around the wading pool, which turned brown after the evacuation.
They think two chemicals — that shouldn't have been mixed — somehow ended up in the water at the same time.
Varennes city officials say the incident was likely caused by malfunctioning pool maintenance equipment.