Prime Minister Justin Trudeau marked the third anniversary of the attack at the National War Memorial by calling on Canadians to pay tribute to the soldier who was killed.

Cpl. Nathan Cirillo was shot while standing guard at the memorial, during a day of terror at Parliament Hill in 2014 that ended with a masked gunman being shot and killed.

Cpl. Nathan Cirillo, 24, was killed while standing guard at the National War Memorial in Ottawa on Oct. 22, 2014. (Facebook/Canadian Press)

In a statement issued Sunday, Trudeau also called on Canadians to honour the bravery of first responders during the attack.

He also honoured Warrant Officer Patrice Vincent, who was killed two days earlier that year in an attack in Saint-Jean-sur-Richelieu, Que.

The prime minister said he thanked Canadian men and women in uniform at large for putting their lives in harm's way to defend the country.

He added that Canada emerged stronger than ever in the wake of the attack.

"These attacks were intended to instil fear and divide Canadians. Instead, they only served to unite us," said Trudeau.