Four children at a Rosemont elementary school were hospitalized after being exposed to bear spray on Thursday morning.

A child spotted the canister of bear repellant in the alley next to the schoolyard of Alphonse Desjardins Elementary School at around 8:00 a.m. A group of kids used a branch to pull the canister under the fence, and one child pulled the pin, setting it off.

An Urgences Sante spokesperson said 22 children were evaluated. The four were taken to hospital due to vomiting, persistent coughs and burning eyes. The children are expected to make full recoveries as the effects of the spray are temporary. 

"The bear repellant, it's in the lower concentration available at Canadian tire or or whatever, but no, it's not something you playfully use on other people. Once in a while you will have someone who has either asthma or another reactive airway disease who will react so strongly to the effects of that," said Urgences-Sante spokesperson Stephan Gascon.

Several other children were treated at the scene and were picked up by their parents to recover at home. 

The origins of the bear spray canister are not known. 

Classes at the school were not interrupted.