Yes, a few years ago my son was in a bus crash and had a serious injury. As they removed the kids from the bus and put them in the median, several cars had stopped. One was a family with an off duty police officer and his wife. They stopped and sprang into action without a second thought. The woman held my son and the man talked to him and kept him calm until the paramedics could load him onto the ambulance.
The paramedic who assisted him was also fantastic. He was terrified and crying for me and I was 40 minutes away and it took awhile to get there. All 3 of those strangers helped him cope through those first moments of the worst trauma of his 12 year old life. That in turn helped me to get through the surgeries and such that followed for him.
I don't know who any of them were by name, so was not able to go back and thank them after the chaos and I sure wish I could. Everyone that day from the medics, the life flight crew and the strangers who stopped to help are always at the back of my mind. When I sometimes lose faith in humanity; I remember people like them and it reminds me that at their core, most people are actually very good.