Police say the man, a 64-year-old Kronos employee, was struck at 6:50 a.m outside the Transport Robert company building — a business affiliate of Kronos.
About 30 people were protesting this morning as part of a contract dispute with Kronos when a driver tried to enter the site with his SUV and one of the protesters was struck by the vehicle.
The man suffered serious injuries to his face and is being treated in hospital. Two other people were treated for shock.
Longueil police spokesman Marc David says the47-year-old driver was arrested for assault with a weapon, but investigators are questioning to find out exactly what happened.
About 300 workers from the Kronos Boucherville plant have been locked out since negotiations broke down June 15. The company specializes in the production of titanium dioxide pigments, which is used in plastics and construction materials.