Here's some of what members of Parliament and other witnesses saw and heard after gunfire started just before 10 a.m. ET:
Jan Lugtenborg, tourist from Holland who was near the war memorial:
"We were waiting there for a city tour and suddenly I heard four shots. No fireworks can be possible during the day. Suddenly I saw a small guy with long black hair ... with a long rifle and he ran away after the shots, across streets in the direction of Parliament HIll."
Marc Garneau, MP, on Parliament Hill for Wednesday morning caucus meeting:
"The caucus is on the ground floor at the back and somebody rushed in from one of the security guards and said ... 'We've heard shots, let's evacuate the building.' On our way out, somebody said, 'Those shots were from outside, let's stay in the building.' And a minute later, somebody said, 'No, those shots were from the inside, let's get out of here.' So the usual sort of chaos that is perfectly normal in situations like this.
"We could smell that gun powder. So we all stood outside waiting for further orders. I did see the prime minister's calvacade and three armoured SUVs appear in the back. So I assumed he was being evacuated. Police started to appear with machine guns and obviously the security machine, if you like, was ramping up and we stood there and waited for further instructions and eventually a bunch of security people evacuated us away from the parliament buildings and so we're no longer there."
Raivo Nommick, resident working near the war memorial:
"I was just passing ... all of a sudden I just heard a shot, turned around and there was a guy with a rifle....and just pow pow. And then I saw one of the other Armed Forces guys just running. He barrelled over, just ran right over. The other guy just dropped.... I looked back and just dived underneath and immediately called 911."
Sandra Bales, works in MP Scott Armstrong's office on Parliament Hill:
"I stuck my head out of the office door, thinking, 'What's going on?' I saw someone running up the stairs and knew something immediately was wrong, locked the door, turned off the lights and crawled under my desk and basically stayed there for 20 minutes until security came by, guns drawn. They said, 'You're doing the right thing. Stay where you're at.'"
MP Kevin Lamoureux, who had just arrived for caucus meeting:
"I just personally thought it was like a fire alarm or something of this nature. So I casually took my time getting out of the room. And then, upon exiting the room, I hear this rapid gun fire and it was very, very loud and instantaneously, you know that there's something seriously wrong here and you could see people in a little bit more of a hurry to exit. At the time, I thought maybe it was just down the hall or around the corner because it was so, so loud."