Paramedics, firefighters and the hazardous materials team responded to the scene at about 3:10 p.m. ET. The hazardous materials team analyzed the package more than an hour later and it was deemed to be "non-hazardous."
"The situation has been resolved," Ottawa police said in a tweet.
The main door of the Centre Block building was roped off for a time and some people who were on a tour were removed from the building.
None of the three people in isolation showed any symptoms, according to Ottawa paramedic spokesman J.P. Trottier.