A "Port Runner" is an individual that has entered the US at a Port of Entry and speed through to avoid being inspected.
It is a felony and a great risk to the Immigration and Customs Inspectors, as the subject usually attempts to run us over.
I had a guy take off will I had my arm in his window. Damn near ripped it off. I've also had them run over my feet.
I can only speculate, but I would bet the subject attempted to hit the CI with his vehicle.