If you are currently a licensed EMT or EMT-P (Parametric) in my state, Washington, then you have an obligation to stop at accidents and lend aid to others, even off-duty. If you are not currently maintaining your license, like me, then you have a choice to lend aid or not. If you do start aid, however, then you can not leave the patient until you pass she/he off to a higher medical authority. You can not ABANDON the patient. That might create a dilemma if you were out in the woods and wanted to go for help and no one else was here. (personally, I would never leave the patient alone, never ever.)

If you voluntarily help a person in Washington State you are protected by the "Good Samaritan" law and cannot be held liable unless you do something ridiculous like put a tourniquet around their neck and kill them on purpose.
BTW... you did the right thing by getting someone with medical training. When you have medical training (even first aid training) you at least know what to do and that is the key to keeping calm and taking control of the situation.