Speculation is rife on social media about the shootings around the Canadian Parliament today, with many users blaming the radical militant group Isis (Islamic State).
The gunmen's long coat and "white scarf" have fuelled speculation that it was an IS-inspired attack, while many believe the timing of the assault points to the Jihadi group.
The shooting came just hours after Martin Couture Rouleau, a Canadian Muslim convert, carried out a lone wolf attack near Montreal.
One witness to the Parliament Hill attacks said the gunman "looked like someone who is Arab, but I am not sure. He had long hair."
Another witness told CBS news that one of the gunmen wore "a scarf with Arabic writing on."
Ontario Premier Kathleen Wynne spoke defiantly in reaction to the news, saying: "Our belief is that people who are using violence to undermine democracy want us to be silenced and we refuse to be silenced."
One of the gunman has been reportedly shot dead inside the building. It remains unclear how many gunmen are currently still carrying out the attacks, or whether they are Arab or Muslim.
Social media frenzy
Twitter has been inundated with speculation in the wake of the attacks, with many speculating that the shootings were carried out in retribution for Canada's decision to join the US-led coalition against IS in Syria and Iraq.
At least 30 Canadian nationals have been revealed to be fighting for Islamic State. A further 130 Canadians are believed to be fighting for different groups in Syria and Iraq.
One Canadian national fighting for IS, known by the nom de guerre Abu Turaab al-Kanadi, allegedly warned of some sort of homeland attack just days beforehand.
He wrote on social media: "Don't regret it when u see retaliation in your own homes".
It is unclear whether al-Kanadi knew about the Ottawa shootings beforehand, or whether his threat was referring to the earlier shooting in Montreal.
Abu Turaab, whose real name is Mohammed Ali, left his home in Mississauga on 17 April 2013. He travelled to Syria and joined Islamic State.
The 23-year-old has been an avid social media user and he has repeatedly created new accounts after they were deleted.
Another alleged IS supporter tweeted: "soldiers of the Islamic State are everywhere around the world." Known as Mohammed Atta al-Khilafa, the account holder tweeted the message to France 24 after hearing about the Ottawa shooting.
Other IS supporters have praised the attacks, but no Islamic State spokesman has directly claimed any involvement in the attack.