Do you use side mirrors? Just wanted to know. Maybe it have helped you to know in advance that someone is coming behind on your back.
Once something similar happened when i was on road. I was driving my bike and there was a car in front of me too. Suddenly the car stopped, i stopped too as i was keeping my eye on him. In 1 to 2 seconds a 125 came and smashed into the car. That 125 guy was only 6 inches away from me. I thanked ALLAH for he did not crash into me.
He was driving very fast and therefore could not stop it. After the hit the car went away and did not even look behind to see what happened, typical Pakistani attitude. His bike was totally smashed from the front, a dent in the car too. The bike owner was left yelling on the road, he too had few bruises. But he was on his feet and nothing serious.