Ottawa Paramedics say 15 children have been taken to hospital after they were exposed to an unknown substance on a school bus.
Ottawa fire officials said the hazmat team was called to Kaladar Avenue off of Heron Road around 9:30 a.m. Thursday.
Paramedics said up to 40 children were exposed to the substance and several were showing signs of nausea, vomiting and coughing.
Ottawa's French Catholic school board has since said the probable cause of nausea and breathing problems experienced by the 15 students at Lamoureux School is the warming up of the bus brakes.
Those that were hospitalized were all in stable condition.
One student was taken to CHEO, but has since returned to class, according to the school board.