The exact number of gunmen involved in the attack is still not known.

The police has started investigating the shooting incidents.

The Ottawa Police tweeted: "#Ottpolice and @RCMPGRCpolice investigating several shooting incidents in downtown #Ottawa.Incidents occurred at National War Memorial, near the Rideau Centre and Parliament Hill this morning. #ottnews."

"#Ottpolice and @rcmpgrcpolice are asking the public to stay away from the downtown Ottawa area. Ongoing investigation.All Ottawa Police building remain in lockdown and closed to the public. #ottnews," it said.

Multiple shooting incidents have been reported from the city.

MP Tony Clement tweeted: "Still patiently awaiting rescue here in Centre Block. I feared this day would come, and my prayers are with the fallen soldier. Hug your fam.Notified to remain in place inside Parliament. The area is still dangerous, and I put my faith in first responders and the Lord above."

The shootings occurred after the nation raised the terror threat level after a fatal hit-and-run attack on two soldiers recently, reports said.