The shootout prompted MPs to pile chairs against wooden meeting room doors to shield themselves from the gunman, forced the lockdown of much of the downtown core and left a suspect dead in the Centre Block.
MPs and senators have been nervous for years about how easily members of the public can access the Parliament Buildings. Canada's role in the campaign against militants in the Middle East has heightened concerns in recent weeks.
Two years ago, the country's auditor general called for better security measures on the Hill.
Four separate bodies watch over Parliament Hill — the RCMP's Parliament Hill detachment, the House of Commons Security Services, the Senate Protective Service and the Ottawa police, which is responsible for the city streets surrounding the buildings.
In a 2012 report, Auditor General Michael Ferguson suggested unifying the security forces "under a single point of command, making it possible to respond to situations more efficiently and effectively."
In the aftermath of Wednesday's shootings, Liberal MP Marc Garneau said security procedures will have to change.
"I think the intention was to try to make Parliament not look like Fort Knox," he said. "But we've crossed a river today."
Garneau pointed out that while visitors go through metal detectors, most parliamentary offices are easily accessible once those people are in the buildings.
"The point is, somebody who decides that they want to rush the building can walk up, rush in, show their weapon and then rush into the building before anybody can really effectively do anything," he said.
Karl Belanger, principal secretary to NDP Leader Tom Mulcair, said there's no question procedures will need to be reviewed and fixed so that such a breach never happens again.
NDP MP Charlie Angus said that as gunfire echoed through the Hall of Honour during the party's caucus meeting on Wednesday morning, "suddenly those parliamentary caucus doors looked very, very flimsy."
But Angus added he hopes the Hill doesn't become fortress as a result of the shooting.
"I just think what's really important to remember from this is that Parliament Hill is an incredible public place that's open for people to play football and come and protest and sit and have their lunches, do their yoga," he said.
"We can't lose that. We need to make it more secure, we need to make sure people can be safe ... but we can never lose sight (that it's) an open place where Canadians feel welcome."
Liberal MP John McKay had the same feeling.
"That building is the people's building and we've been able to pride ourselves on its accessibility to people," he said. "I hate to think of us shutting it down because of both paranoia and legitimate fears. It really changes everything."
Ferguson's report, however, made reference to a 2009 security breach that involved Greenpeace protesters scaling the West Block and unfurling a banner.
"Subsequent analysis revealed that the House of Commons Security Service's mandate covered the area inside buildings under its jurisdiction and the RCMP's mandate covered the grounds, but no organization had a clear mandate for the roofs of the building," his report found.
Some MPs recently asked for a Commons committee hearing into momentary delays inflicted upon parliamentarians last month as they tried to get to the House of Commons and were held up by the German president's motorcade.
MPs say their ability to move freely is a question of parliamentary privilege, ranking with their right to call for witnesses and documents and to say what they want in the Commons.
The hearing was held Tuesday, the day before the shootings.
Late last year, the RCMP added new video cameras near pedestrian entrances to Parliament Hill, and a vehicle screening facility along Wellington Street, the boulevard in front of the Parliament Buildings.
Some cameras can record panoramic views and closeup images. The RCMP apparently monitors the video stream round-the-clock, with simultaneous feeds to House of Commons and Senate security personnel.
Internal RCMP notes released under the Access to Information Act said the plan was to increase video coverage of the parliamentary precinct to 100 per cent from 35 per cent.
The Mounties also said the system is intended to guard against a possible attack by detecting abandoned packages, suspicious activity and disturbances.
— With files from Joan Bryden in Ottawa
Follow Lee-Anne Goodman on Twitter @leeanne25
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