OTTAWA, Canada -- Shots that rang out in the Canadian capital Wednesday left a soldier and a gunman dead, a city on lockdown, and a series of questions about security threats facing the nation.
Parliament member Kyle Seeback called it a "horrific day."
Authorities in Ottawa said they were searching for at least one other possible shooter.
There were two shooting incidents in the city, where this kind of violence is extremely rare: one at the Canada War Memorial, which is near the Parliament building, and another round of shooting inside Parliament.
"I was locking my bike up, and I heard four shots," said Peter Henderson, a journalist who was at the memorial at the time of the shooting. "I saw one of the soldiers laying on the ground."
The soldier appeared to have been shot in the back, Henderson said. Other soldiers who were nearby doing drills at the time ran to help, he said.
"This is a dynamic and unfolding situation. I understand that people have many questions and we are committed to providing some answers as soon as we are able," Assistant Commissioner Gilles Michaud, commanding officer of the Royal Canadian Mounted Police National Division, told reporters Wednesday.
In Twitter posts Wednesday, several Canadian lawmakers hailed a top security official as a hero, crediting him with shooting the gunman inside Parliament.
"MPs and Hill staff owe their safety, even lives, to Sergeant at Arms Kevin Vickers who shot attacker just outside the MPs' caucus rooms," Craig Scott, a member of Parliament, wrote.
'I heard rapid fire'
A gunman entered the nearby building on Parliament Hill, officials said.
"I heard rapid fire -- gunshots going very loud -- and I figure maybe 20-plus shots within 10 seconds," Canadian Deputy House Leader Kevin Lamoureux told CNN. He was one level below the gunshots.
Soon, Lamoureux and others were outside the building, taken to another building nearby for safety. Others still inside were on lockdown. Some members of Parliament said on Twitter that a gunman had been killed. Police say "one male suspect" is dead.
Canadian authorities have given the name of a suspect to U.S. law enforcement and have asked for FBI assistance in tracing the person's activities, a senior U.S. law enforcement official told CNN. Only one name has been provided, and it is not clear whether the name is genuine or an alias, the official said. The official declined to provide more details, including the suspect's nationality, ethnicity and age.
A U.S. law enforcement official told CNN that a connection to terrorism hasn't been ruled out.
On Monday, a man who Canadian authorities said was "radicalized" killed a Canadian soldier with his car. The man was then shot and killed.
There was no immediate indication that the Monday and Wednesday incidents were related.
In response to the shootings, the North American Aerospace Defense Command, or NORAD, has increased its alert posture, CNN has learned. That means that it has increased the number of planes on a higher alert status ready to respond if needed. NORAD and Canadian authorities are in contact, an official told CNN.
Parliament remained on lockdown at mid-afternoon.
Prime Minister secure
MP Tony Clement tweeted that he heard "at least 30 shots" and apparently was able to take cover with colleagues. He also tweeted that Harper was secure.
Harper was evacuated from the building and is safe, tweeted his press secretary, Carl Vallee.
Hours after the Parliament attack, Harper spoke by phone with U.S. President Barack Obama.
Ottawa Mayor Jim Watson said that Wednesday was a "a sad and tragic day for our city and our country."
"There's no pain greater than losing a loved one -- to have it happen in such circumstances as this morning is beyond expression, and underlined by a sad anger within my heart," he said.
Gunfire in the main Canadian Parliament building started in the foyer, and a second round of shooting happened about a minute later in a hallway or near the entrance to the Parliament's library, Ottawa journalist Josh Wingrove told CNN.
He said several officers had weapons drawn, and most of the dozens of shots that he heard appeared to have been fired by officers at the gunman.
When the shooting ended, a person was lying motionless on the ground near the library entrance, Wingrove said.
Police were searching unlocked rooms in Parliament, the journalist told CNN.
Meanwhile, authorities are trying to get a handle on a chaotic situation.
"We don't know if it's someone from the military who was targeted or not," Marc Soucy of the Ottawa Police Service told CNN. He was specific about when gunfire was reported: 9:52 a.m. ET.
Parliament member James Lunney tweeted: #HOC in Lockdown, lone gunman shot security guard, shot his way down Hall of Honor....we are all safe. Gunman dead! Thnk God & our scrty!"
Canada raised its terror threat level
Obama was briefed on the situation in Ottawa, White House officials said.
The violence at Parliament comes just days after Canada raised its terror alert Friday.
The suspect in Monday's vehicle attack, Martin Rouleau Couture, reportedly converted to Islam about a year ago. Police arrested him last July and confiscated his passport, but lacked enough evidence to keep him in custody, said Martine Fontaine of the Royal Canadian Mounted Police.
"When he was arrested, he was about to go to Turkey," Fontaine said. "We stopped him as he was about to leave Canada for terrorist actions. He was questioned when he was arrested. We have not been able to determine any real threat at this time."