The gunman entered the building at a busy point in the weekly schedule when the party caucuses meet there and journalists and staff gather outside the caucus rooms. Most MPs were in the building at the time.
For NDP press secretary Greta Levy, the attack left an indelible memory. Levy was leaving Centre Block with her colleague, NDP press secretary Marc-André Viau. They both saw two women hit the ground, and then heard someone yell at them to get down. The moment was so tense that Viau didn't realize until later that the women were reporters he's known for years.
In an interview with Evan Solomon, host of CBC Radio's The House, Levy described seeing the gunman.
"I looked up and I saw him immediately and only him. I have no recollection of seeing the car, of seeing people chasing after, I didn't notice anything else. And I just saw a young man ... when I saw him he was striding, not running, and then I saw the gun in his hands and immediately dropped my head," Levy said in the interview, which will air Saturday at 9 a.m.
Once the shooting was over, the two hurried down the Hill toward Wellington Street.
Viau ran into a flock of reporters across the street from Parliament's front lawn, where he answered repeated frantic questions for at least half an hour as police expanded the security perimeter. He started getting requests for interviews from Canadian and foreign news outlets, which he granted until 11:30 p.m.
'I'm not doing OK'
Levy said it only struck her hours after the attack that she could have been shot.
"I don't know why it took me so long to understand that. I mean, that's obvious, you know, if I can see him, he can see me and we were all lying down on the ground and he was standing. But I guess that game can be played a million different ways and the fact is that he chose to bypass us and so, yeah, we were at the wrong place at the wrong time, but had we come out one minute later, it would have been a much worse place."
Parliament resumed Thursday, the day after the shooting, and the House sat until just after noon on Friday, ending only slightly ahead of its normal Friday rising time.
But it was difficult for a lot of people to focus on work.
"I'm not doing OK," NDP Deputy Leader Megan Leslie told Evan Solomon.
"And I think anybody who tells you they are, either the emotions haven't hit them yet, they haven't processed it yet, or they're not being truthful."
Conservative MP Rick Dykstra said he's still dealing with the events too.
"I haven't processed it all yet. I did a little bit. I started to come to grips with it yesterday," he said.
"But I realized how close to danger we were and what happened at the war memorial, and how quickly it all transpired. I think most of us are still processing it and I'm still dealing with it as well."
"Some people can get through these things and issues in a very, very quick way mentally, and I think others are going to reflect and they're going to feel it this weekend or next week."
The House of Commons is offering employees assistance, with drop-in counselling sessions already arranged for three days, and encouraging people to take advantage of them. The House has also arranged for counselling after-hours for those working evenings. In a memo to staff advising them the House would resume sitting at 10 a.m. the day after the shooting, acting clerk Marc Bosc told those who felt unable to work "due to the day’s events" to speak to their supervisors.
MP staff members and political research staff also have access to those programs, and the NDP extended the assistance to interns and volunteers.
The Privy Council Office, whose staff work in a building on Wellington Street across from Parliament Hill, also arranged support and counselling, which covers the staff of the Prime Minister's Office as well.
Liberal MP Rodger Cuzner said the shooting has taken a lot out of everyone.
"You can see it in the faces of staff," he said. "We probably have more than a thousand people on the Hill here, so I know people will be looking forward to their weekend."
Leslie said all the MPs are "walking around like zombies, just going through the motions." Everybody on the Hill, she said, is exhausted.
Two of the clerks, she added, "were in the Hall of Honour ... hiding behind a plywood desk for three hours. The Library of Parliament staff are going into work crossing over the exact spot where a man was shot and killed just a few days ago. I mean, it's a challenge to be here."