The Canadian capital was rattled with three confirmed incidents of shooting inside the country's Parliament buildings, War Memorial and a shopping mall, media reported on Wednesday.
Canadian Police also said that there is an involvement of numerous gunmen in the shooting incidents.
Latest reports confirmed that a suspect has been shot dead, a US official said while adding that other suspects are still on large.
Witnesses saw a man fleeing the scene in a car toward the parliament buildings, according to Xinhua.
Witnesses also said that at least 20 fires were shot at the Parliament.
Local police and tactical teams soon converged on the area.
Canadian police warned people in Ottawa to stay away from windows and roofs after the shooting.
Police surrounded the Parliament and escorted some lawmakers and reporters to safety.
Canada Prime Minister Stephen Harper left the shooting area safely, reports said.
Meanwhile, North America has been put on high alert following three shooting incidents in Canadian capital, Ottawa.
US President Barack Obama has been briefed on the situation in Ottawa, White House official said.
US, Canada air defences on alert after Canada shooting
The North American Aerospace Defense Command (NORAD) "is taking appropriate and prudent steps to ensure we are adequately postured to respond quickly to any incidents involving aviation in Canada," said the official, who spoke on condition of anonymity.
The shooting comes two days after an Islamic convert ran down two Canadian soldiers, killing one, near Montreal.