This was an alert that went out from the government operations centre warning that there was an armed shooter at loose and that there was a lockdown for federal employees and government buildings in a defined area in downtown Ottawa and that people should stay away from the windows and stay in their offices until they heard otherwise. This was later followed by messages that came from Treasury Board Secretariat that were in both languages, but the initial emergency announcement was in English only.
On October 28th, 2014. See this statement in context.