Helen Macaulay and Andrea Konidis had just arrived in Manchester on Monday when they were caught up in the drama at Piccadilly Gardens.
Helen, a former auxiliary nurse at St John's Hospice, and friend Andrea - known as Annie - who is a palliative care nurse at the hospice, rushed to help after spotting two men screaming in agony on the floor.
"As we walked from the train towards Piccadilly Gardens we saw what looked like a fight, so we went round the corner of Morrisons to see if everybody was OK," Helen said.
"Two men were on the floor screaming and writhing around in agony. We rushed to help them, realising fairly soon that they had been stabbed, and a gang of hooded men were fleeing the scene."
The friends, both 55, attended to the youngest victim, a 17-year-old boy, who had deep stab wounds in his back and shoulder that were bleeding badly.
"We managed to plug the two wounds with rolled up bandages courtesy of Morrisons," Helen said.
"He was drifting in and out of consciousness at this point. He kept saying to us that he was going to die and we were telling him he was going to be OK and trying to keep him warm as best we could on a bitterly cold day.
"The other man had also been stabbed and was being attended to by other members of the public. At this point we didn’t know they were father and son."
When the police arrived at the scene, Helen and Annie were allowed to stay to help, and Annie spoke to the boy's sister and mother on his mobile phone to reassure them.
The police, meanwhile, evacuated the area and taped it off, at the time suspecting a terrorist attack.
Helen and Annie, who both live in Bolton-le-Sands, used police equipment to check the teenager's oxygen levels and pulse, and were relieved to discover both at a good level.
"We then thought we weren't going to lose him because at one point we really thought we might," Helen said.
Once paramedics arrived on the scene the pair left the area, and were welcomed into Morrisons by staff to clean up, have a hot drink and a sandwich, before continuing on their way to meet Helen's cousin for a day of shopping.
"Morrisons were great," Helen said. "We were covered in blood and needed somewhere to have a wash."
The following day, the friends were contacted by Manchester CID to give statements, and were told the attack had not been targeted, and that police were confident they had CCTV images of the men who ran off.
Both the 17-year-old and his father are still in hospital, the older man in intensive care.
"You never know what’s going to happen," Helen said. "A simple shopping trip turned out to be a double stabbing.
"We really thought that they might die while we were there but between us I think we did a good job.
"It’s a far cry from the sleepy village of Bolton-le-Sands where we both live."
Sue McGraw, chief executive at St John’s Hospice, praised current nurse Andrea for her actions.
She said: "“St John’s is very proud of Andrea for epitomising the very ethos of St John’s Hospice nursing - to be there when you are needed.
"Our first thought was how typical of Andrea to rush to the assistance of another person: We witness her care here at St John’s and she is an outstanding nurse.
"Andrea is just the person you would want with you in a crisis and I know her colleagues will be as proud of her as I am.”