Cameras near the front door of the Centre Block captured Zehaf Bibeau wrestling with a House of Commons security guard and shooting at other guards before sprinting down the Hall of Honour, according to two sources with knowledge of the video.
There are no cameras in the hall itself, which runs between the Conservative and NDP caucus rooms.
Zehaf Bibeau was killed in a shootout with security forces at the end of the hall.
The Ontario Provincial Police had access to the video as part of its multi-pronged investigation into the actions of security forces on the day of the shooting.
Heather Bradley, a spokeswoman for House of Commons Speaker Andrew Scheer, said the security footage won't be made public for security reasons.
The much anticipated reports from the OPP will outline the results of an investigation into the actions by the RCMP inside and outside the Parliament Buildings, and the actions of security guards inside the Centre Block.
They are expected to conclude that security guards were justified in shooting the gunman dead.
They are also expected to identify holes in the security system in place on Oct. 22 that allowed Zehaf Bibeau to run onto the Hill, commandeer a minister's car, and get inside the Centre Block in a matter of seconds.
It may also touch on items that have already been publicly discussed, such as a lack of communication between forces inside and outside the Parliament Buildings.
Even internal government communications were a problem on Oct. 22.
An internal government report shows federal workers deleted emails alerting them to events on the day of the shooting because they thought the messages were spam.
Those alerts didn't reach everyone who needed to see them because of a crisis communications system that was "outdated" and has "limited connectivity," according to documents obtained by The Canadian Press.
Cell service was also spotty, since government systems were overwhelmed on the day of the shooting, meaning many emails didn't get through.
The documents from Agriculture and Agri-Foods Canada, released under the Access to Information Act, say not every department followed orders to lock down their Ottawa offices.
Indeed, the documents say the majority of departmental emergency response plans don't even deal with lockdown incidents.
The report, provided to Agriculture Canada's deputy minister as part of a December briefing note, says some government departments ignored the lockdown. Other departments with offices in the same building didn't force their workers to stay sheltered in their offices, the documents say.
In a separate questionnaire, the department told the Government Operations Centre that briefings and security reports during the day didn't help it make timely decisions, pointing to ongoing communication problems.
Agriculture officials wrote that there were delays in receiving messages from the operations centre; those messages were not always clear and at times inconsistent; and a digital portal set up to deal with emergencies "was slow and was not used in any meaningful way."
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