A man with a rifle shot a soldier standing guard at the War Memorial in downtown Ottawa, and witnesses said there were further shots fired in Centre Block on nearby Parliament Hill.
It was not immediately known if there were further injuries.
Alain Merisier, who works at the cafeteria in the Parliament building, told CBC News that said he saw a man in a car at the Centre Block with a long gun.
Witnesses said they then heard shots fired, and there was an unconfirmed report of a person injured outside the Library of Parliament.
Police confirmed the shooting at the War Memorial, and sealed off the area while the injured soldier was given emergency medical aid. He was later put into an ambulance.