Matt Patterson, 30, helped the seven-year-old in the aftermath of the blast which killed her brother Martin.
An Irish dancing student at the Clifden Academy of Irish Dance in Milton since the age of three, the little girl had been watching the parade with her family. An earlier photograph showed Jane and her brother Martin standing just yards away from terror suspect Dzhokhar Tsarnaev.
Captured moments after the blast, the amateur footage shows Patterson, wearing a red t-shirt, rushing to help the little girl who lost her leg in the attack and remains hospitalized in a critical condition. Their mother Jane sustained a severe upper body injury in the explosion.
Just before the explosion, Patterson had been enjoying a meal with his girlfriend at a nearby restaurant, following the bomb blast the firefighter leaped into action.
In the video Jane is seen sitting up in the middle of the road after the blast.
“This child for some reason just jumped at me - it was tunnel vision,” he told AP.
“I could see the damage. I could see that she needed a tourniquet. She needed surgery, it was obvious from what I saw.”
“I go up to a business guy and ask for his belt, he hands it over without hesitation. I have to stop the bleeding. I am making the tourniquet and another man comes and I ask him to hold it for pressure. I'm looking up and down the street - looking for where I can bring the child to an ambulance or more care.”
Patterson alongside another hero ran with Jane in their arms to a waiting ambulance.
On Tuesday, the family laid Martin to rest.
In a statement they said: “The outpouring of love and support over the last week has been tremendous. This has been the most difficult week of our lives and we appreciate that our friends and family have given us space to grieve and heal.
“A private Funeral Mass was celebrated this morning with immediate family. We laid our son Martin to rest, and he is now at peace. We plan to have a public memorial service in the coming weeks to allow friends and loved ones from our community to join us for a celebration of Martin’s life.”
Watch the AP report below: