"The English are waking up!" the shooter, identified only as a 62-year-old man, was reportedly yelling in French, indicating opposition to the policies of the Parti Quebecois, which favor independence for French-speaking Quebec from Canada.
Given that the PQ only won a minority in the legislature, it is unlikely that it will attempt to hold a referendum on independence.
The shooting took place near a back entrance to the building, away from the main auditorium where Marois was speaking. Police said they believed the gunman acted alone.
"At this stage in the investigation, there is nothing to indicate any accomplices or other persons implicated," Montreal Police spokesman Ian Lafreniere told the Vancouver Sun.
The last such occurrence of a politically-motivated killing in Canada occurred in 1970, when a group of radical Quebec nationalists kidnapped provincial Labor Minister Pierre Laporte and a British diplomat, later strangling Laporte to death.