A soldier was shot at the War Memorial, and multiple witnesses reported further shots were fired on nearby Parliament Hill.
At Quebec's National Assembly, security was doubled at entrances and exits and visitors were barred from entering the building and the library.
Foot traffic in the tunnels and outside the building was also restricted.
Helicopters circled the National Assembly in Quebec City and a team of Sûreté du Québec officers arrived shortly after 11 a.m.
Despite heightened security, Question Period proceeded as scheduled.
Premier Philippe Couillard said it was too premature to make any kind of statement on the events in Ottawa.
Coalition AvenirQuébec leader FrançoisLegault agreed.
"All we can do is hope the number of injuries is minimal," he said from inside the legislature at Quebec's National Assembly.
Québec Solidaire leader Françoise David said she has many friends on Parliament Hill and was very concerned about them.
MPs smelled gun smoke, ushered from building
Marc Garneau, Member of Parliament for Westmount–Ville-Marie, told CBC News he was in the Centre Bloc at Parliament in Ottawa.
He said he could smell gun smoke inside the building, but did not hear the gunshots.
Garneau, along with all the other MPs, were ushered out of the building by police.
“People are trying to figure out what the heck happened,” he said.