The public was never in danger from a package found Tuesday at the entrance to the main Defence Department building in Ottawa, authorities say.
Still, an investigation is under way after the package was found to contain items consistent with what is used to make an improvised explosive device, or IED.
An investigation is under way and more details are expected to be released later, Defence Minister Peter MacKay said.
"There will be an investigation into this incident," the minister said in a statement.
"More details will be made public as soon as they are available."
The suspicious package was found at the north entrance of the National Defence Headquarters in downtown Ottawa.
A chemical, biological, radiological, nuclear and explosives team was called in as the busy Mackenzie King Bridge was sealed off and closed to afternoon rush-hour traffic.
MacKay acknowledged the disruptions that were caused by the package disposal operation, but said authorities acted quickly, and properly.
"I wish to extend my thanks to all of the professionals who took the appropriate action, especially the police," he said.
The north tower of the building was evacuated as responders inspected the package.
Police were called about the package around 3:30 p.m. ET. The bridge was reopened more than four hours later.
Ottawa police said an X-ray revealed what appeared to be a timing device and an electronic trigger inside – both consistent with what's found in an IED.
The package was sprayed with water cannon, and eventually removed by a robot and later detonated.
It's not clear, however, whether the package actually contained any explosives.
Ottawa police, the Mounties and Military Police are all involved in the investigation.