Five people were injured in a school bus accident in Saint-Adolphe-D'Howard, about 100 kilometres northwest of Montreal around noon on Wednesday.
According to Quebec police, the bus started rolling backwards as children and adults were boarding it.
A woman who was behind the bus was seriously injured when the vehicle started moving. She was taken to Sacre-Coeur Hospital in Montreal.
Four other people suffered minor injuries.
Police are still investigating the incident.