Their noses peeking out from under the fence, Nathan Cirillo's dogs wait patiently for their dad - unaware that he will never be coming home.

A day after the 24-year-old Canadian reservist and single dad was gunned down in Ottawa on Wednesday, his forlorn dogs could be seen peering out from his family's home in Hamilton, Ontario.

Cirillo was devoted to his animals, posting image after image of him grinning beside them to his Instagram feed. Friends also recounted the story of him recently finding an abandoned, emaciated puppy that he nursed back to heath and then re-homed.

'Found him a pretty home, hope he has a good life,' Cirillo wrote just four weeks ago of the pup.

Cirillo, who was shot dead as he stood guard at the National War Memorial outside the Canadian Parliament on Wednesday, also leaves behind a six-year-old son.

He was bringing up the boy, Marcus, alone - with help from his mother, Kathy - after the boy's mother was no longer in the picture, friends have said.

Former girlfriend Randi Lotsberg said that Cirillo lit up whenever he spoke about his son.

'He stepped up. Definitely admirable,' she told The Star. 'I feel so bad right now for his kid. Now his son doesn't have a dad.'

He met the boy's mother, Kendra, at the Ancaster Fair in Jerseyville after he was kicked out for not paying to get in. Outside he met Kendra and a friend, who asked for a ride home,Metro News reported. They dated and went on to have Marcus.   

Cirillo's mother Kathy, who is traveling to Ottawa, will now likely take care of Marcus, CBC reported. She took care of him when Cirillo was working or away on his military duties, Lotsberg said.

Nathan's uncle Jim Cirillo told reporters from a home in Hamilton that the soldier's mother is in total shock.

'She's saying she doesn't believe it,' he told CBC. 'She went on the internet and she saw it and she...I don't know how she didn't pass out. She's just completely broken, broken right now.'

Hamilton Mayor Bob Bratina said that he had visited a makeshift memorial to Cirillo outside his regiment's barracks before going to the family's home with Police Chief Glenn De Caire.  

As he spoke to the slain soldier's relatives, little Marcus wandered out to greet everyone. He likely didn't understand what had just happened, the mayor said.