Dannii McLaren, a volunteer at St John Cymru Deeside and Mold was out at her local supermarket when a woman collapsed.
Dannii 20, said: “I was shopping at Asda when I heard the announcement and I asked staff if they needed me. A lady was on the floor quite confused.
“I took observations and reassured her as best I could. I kept talking to her to make sure she was okay until the ambulance came.”
Paramedics responded with a Rapid Response Vehicle and one patient was treated at the scene.
Dannii added: “I’m grateful for the training from St John Cymru, it’s very real so I think a lot of people should learn first aid and know how to help.
“I love being a volunteer. I've volunteered for three years now and it's really surprising at just how many people don't know even basic first aid.
"I would encourage people to just try and learn first aid because you never know when you may need to use it and it can save lives.”