A 24-year-old soldier who was gunned down as he stood ceremonial guard at the National War Memorial in Ottawa was described as a "kid at heart" at a funeral service packed with family, friends and dignitaries.

Prime Minister Stephen Harper was among those who paid tribute to Corporal Nathan Cirillo at the full regimental funeral in Hamilton.

Harper talked about the "gut-wrenching" irony that Cirillo was killed guarding the Tomb of the Unknown Soldier but said Cirillo knew what he was protecting.

He added that he hopes the soldier's young son may some day find comfort in the fact that the entire country looks up to his dad with pride, gratitude and deep respect.

Lieutenant-Colonel Lawrence Hatfield, commanding officer of Cirillo's Argyll and Sutherland regiment, praised him as a soldier of character whose warm and radiant smile exuded "unmistakable confidence."

Hatfield said that while bullets took Cirillo's physical life, his attributes have illuminated Canada.

Cirillo's cousin, Jenny Holland, said he was a rambunctious, smiling, adventurous child who remained a kid at heart and loved playing with his five-year-old son, Marcus.

In a homily, Reverend Canon Rob Fead called Cirillo "Canada's son" and said his death was not in vain because it had helped bring the country together.

While only those who were invited got into the service, it was broadcast outside for others who wanted to pay their respects.

Near the church, people lined up four deep to watch the procession that brought Cirillo's casket to the service, many of them holding Canadian flags and balloons emblazoned with the Maple Leaf.

At one point on the route, a group of young women sang the national anthem, drawing cheers and applause from the crowd.