"Our democracy cannot and will not be intimidated by today's events," Moore tweeted Wednesday night.
Prime Minister Stephen Harper said Canada will not be intimidated.
"In fact, this will lead us to strengthen our resolve and redouble our efforts, and those of our national security agencies, to take all necessary steps to identify and counter threats and keep Canada safe here at home," he said in an address to Canadians.
Parliamentarians, staffers and others will return to work one day after a gunman walked into the building just metres from the room where Prime Minister Stephen Harper met with his caucus.
The question on many minds is: How will it be different.
Will the stone walls and marble floors bear the pockmarked scars of the shooting? Will the broken glass, shattered when police burst through doors to search offices for intruders, be swept up? And, if security is tightened, how will it change how things work?
Security stepped up in recent years
RCMP said Wednesday afternoon that the threat level on Parliament Hill won’t change, but that doesn’t mean security measures won’t.
Indeed, while parliamentarians want to sit as usual Thursday — Senate Speaker Noel Kinsella also said he expects senators to be in their seats at the normal time — the Hill will be closed to visitors.
In the 13 years since the Sept. 11 attacks in the U.S., Parliament Hill has dramatically increased security while keeping the grounds around the buildings wide open.
There’s even an open yoga class every Wednesday during the warm summer months where participants spread their brightly coloured mats around the front lawns. Canada Day sees tens of thousands of revellers crowd the area, and a sound and light show entertains people every night at the height of tourist season.
In the past few years, security has been stepped up even more, with the grand stone wall along Wellington Street extended to close off some entrances and retractable bollards — essentially big concrete cylinders — installed to control the remaining ones.
The number of surveillance cameras has quadrupled and all visitors, even those escorted by someone with a Hill pass, have to go through security at the entrance to Centre Block.
Liberal Leader Justin Trudeau said criminals will not dictate how Canadians govern the country.
"They cannot and will not dictate our values. And they do not get to decide how we use our shared public spaces," he said in prepared remarks Wednesday night.
Country blessed by peace
Green Party Leader Elizabeth May urged calm while law enforcement officials investigate what happened.
"Today is not a day that 'changes everything,'" she said in a statement.
"It is a day of tragedy. We must ensure we keep our responses proportionate to whatever threat remains."
It's hard to tell in the immediate aftermath of a shocking event just how much will change. It's just as hard to know whether those changes will last.
There were moments Wednesday where some of it seemed routine: journalists waited outside with the same colleagues with whom they've staked out dozens of closed doors and public events. The newsrooms, albeit locked down, throbbed with the energy that only comes with the biggest of breaking stories.
For the staffers locked inside their offices, advised to stack furniture to block the doors, hearing the police smash through neighbouring rooms to ensure no one was hiding, heading to work will likely feel a lot different.
After all the chaos and horror, NDP Leader Tom Mulcair sounded a reassuring note.
"Canada is shaken today but we shall not waver. We woke up this morning in a country blessed by love, diversity and peace. And tomorrow, we will do the same."