What if you knocked down a dog?

Driving is one very interesting activity. While it's convenient, comfortable and fun it carries such a huge responsibility with it. Today i ran down a dog, it's quite sad since i heard the dog crying with pain while i was driving over it. It was an accident i wish i could have avoided, but i saw one dog crossing the road and i braked for it to cross, i quickly thought phew how lucky and then out of nowhere two other dogs came after it, i don't think those two dogs were checking to see if there were cars on the road, i think they were just following the first dog and opps they just crossed right in front of my wheels. It was too late for me to stop and i think i knocked one down and the other one escaped luckily so i believe since i heard only one crying with pain while i was driving over it. I didn't have the courage to look back or slow down after the incidence.

Am wondering what would be the best thing to do in such a situation, a friend of mine told me that i should have reversed and killed it quickly instead of leaving it to die a slow and painful death but i think that is too harsh and ruthless. Stop and take it to the vet? but where would i get the courage to do that?

Best thing to do it to try and avoid as much as possible such an incidence and of course pray that obstacles are eliminated as much as possible along your driving lane.