- Sources: Michael Zehaf-Bibeau was the suspected gunman
- Prime Minister Stephen Harper calls the gunman a "terrorist"
- Cpl. Nathan Cirillo, a Canadian soldier, was shot and killed
Canadians feared this day, hoping it would never come but also knowing the odds probably weren't in their favor, either.
Not in this era of senseless gun violence, homegrown jihadists and terrorist organizations with international reach.
On Wednesday, a gunman opened fire in the heart of the Canadian capital, shattering a nation's sense of security.
There are unanswered questions: What prompted the attack? Is there a link to terrorism?
Whatever the answers, one thing is clear: As one resident put it, "Canada lost its innocence today."
This is how it unfolded.
Chaos in the nation's capital
It begins at Canada's National War Memorial.
A blaze of gunfire erupts at the solemn National War Memorial in Ottawa. Two soldiers are standing guard. One of them is gunned down.
"I heard four shots," says Peter Henderson, a journalist. "I turned around and ran, and I saw one of those soldiers laying on the ground."
The shots sound like they come from a high-powered rifle, Henderson says. Other witnesses describe the shooter as a man with dark hair and a scarf on his head. They say he's carrying a "huge rifle."
Strangers and emergency personnel rush to the soldier's aid as the gunman runs away. At least one witness says the shooter commandeers a car at gunpoint and leaves the scene.
The action quickly shifts to Parliament Hill, just a quarter-mile away.
Shortly before 10 a.m.:
Witnesses report a gunman entering the main Parliament building through an entrance meant for government officials. He exchanges gunfire with security officers.
"I heard rapid fire of what appeared to be 20 shots or more, very loud, appeared to be very close," says Kevin Lamoureux, a member of Parliament.
Canadian Prime Minister Stephen Harper is holding a meeting at the time. He is quickly escorted, along with some members of Parliament, to a safe location, but dozens of others remain inside on lockdown. MPs and Parliament staff barricade themselves in rooms throughout the building.
Within minutes, the shooting is over, according to Josh Wingrove, a reporter with The Globe and Mail newspaper who was at Parliament when it began. He sees a body outside the Library of Parliament.
Locked behind closed doors, government officials wait while police clear the building and make sure there are no other gunmen inside. They take to Twitter to keep friends and family posted on developments.
MP Michelle Rempel tweets to let her mom know she's OK.
Sen. Jim Munson describes the harrowing experience. "Everyone safe but shaken ... mp's say they could smell gunpowder," he tweets.
Although Wingrove sees the body in a hallway, it will be hours before official word comes that the gunman is dead, killed by Sergeant at Arms Kevin Vickers.
Chaos in downtown Ottawa
Ottawa police don't know how many suspects they're looking for. They tell CNN there may have been two or three shooters and the war memorial. Officers flood the area.
CBC reporter Chris Goldrick tells CNN that authorities believe there's another gunman at large and on the run.
There's word of yet another possible shooting, police say. This one is just a seven-minute walk from Parliament, near the city's Rideau Centre mall. That report is later dismissed.
Just before noon:
The U.S. Embassy in Ottawa goes on lockdown. President Barack Obama is briefed on the shooting and pledges Washington's support.
U.S. Secretary of State John Kerry passes along the message to John Baird, Canada's foreign minister.
Minutes later, developments in Ottawa prompt NORAD -- the North American Aerospace Defense Command -- to put its planes on higher alert. "We stand with you," says a statement from Cmdr. Chuck Jacoby.
The FBI pledges to remain vigilant after recent chatter by ISIS about attacks on Western targets. The Canadian Embassy in Washington is also locked down.
Just after 1 p.m.:
News comes that that the Canadian soldier who was shot at the war memorial has died. He's identified as Cpl. Nathan Cirillo, a reservist from Hamilton, Ontario.
Later in the day, Canadian officials tell their American counterparts that Michael Zehaf-Bibeau is the suspected gunman, multiple U.S. officials told CNN.
Zehaf-Bibeau, who was born in 1982, was a convert to Islam and had a history of drug use before he converted, two sources say.
His passport had been confiscated by Canadian authorities when they learned he planned to go fight overseas, a U.S. law enforcement official says. The official said it is not clear when that happened.
Canadian broadcaster CBC reports that Zehaf-Bibeau had a record of drug arrests going back 10 years.
The end of the day
Wednesday closes with lots of uncertainty for the people of Canada, but especially for the residents of Ottawa. Are more attacks planned? Are there any other gunmen on the loose?
Still, there are signs of hope and goodwill.
In Pittsburgh, the CONSOL Energy Center is bathed in red and maple leaves as the Canadian national anthem plays before the NHL match between the Penguins and the Philadelphia Flyers.
Back in Ottawa, MP Rempel reminds those who were shaken by the incident that not all is lost.
"For those wondering, our nation's flag still proudly flew over parliament hill tonight. #CanadaStrong," she tweets.