That confusion, moments after the shootout in Centre Block, the main building of Parliament, has one MP calling for a unified security service.
Parliament Hill is a mishmash of jurisdictions, with the Ottawa police responsible for the area around the Hill, the RCMP in charge of the grounds, and separate House and Senate security services working inside the buildings.
New Democrat MP Charlie Angus says he and 11 other MPs were ushered by House security out of the caucus room in which the party was meeting at the time of the shooting and sent down the hallway to the Senate side of Centre Block.
The plan was to take a tunnel from Centre Block to East Block. But when the MPs encountered Senate security, Angus said, they were told they had to leave the building.
"So we ended up on the front steps … and they closed the door behind us," Angus told CBC News.
"I look around and realize there's absolutely nobody else on the steps of Parliament except 12 MPs walking around."
'Could have been catastrophic'
The MPs rushed to the East Block and rang a buzzer at a back door, but Angus said they were told the building was under lockdown and that they had to go around to the front of the building to enter.
At the time, just minutes after the shooting, it wasn't yet clear whether there was more than one intruder on Parliament Hill or anything else that might put people at risk.
Angus said the MPs were told they had to circle the building to the main entrance to be let in — passing one exit onto Wellington Street in the process — so they decided they might as well leave the grounds entirely. The MPs walked down Wellington Street and were locked down in Angus's office farther away from Centre Block.
The MP said he doesn't blame Senate security for the confusion.
"But if this ever happens again, this is not that big a building. We can't have four different jurisdictions trying to figure out what's going on and getting people safe. So I come forward to say something went wrong here, something could have been catastrophic here, thank God it wasn't, but let's make sure we learn from that."
"They were obviously not communicating," Angus added.
Radios now communicate
CBC News reported Monday that the House, Senate and RCMP all use different radio frequencies, making it difficult to communicate quickly in an emergency.
Senate government leader Claude Carignan said Tuesday that problem has been fixed.
"I understand they are all on the same frequency [now]," he told CBC News.
Carignan's spokesman, asked to clarify when the radios had been put on the same frequency, refused to say, citing security concerns.
Asked why security concerns didn't prevent Carignan from discussing the radio frequencies to begin with, Sébastien Gariépy couldn't answer.
The auditor general found in 2012 that the various security services needed to be more integrated. He found, for example, that no one would take responsibility for securing the roofs of the buildings.