The fact that the jet overran the runway suggests to me either (1) pilot error or (2) total brake failure. I'd bet a dollar on the former.
That's insane. In spite of it, for all the flying they do, it really is still, the safest way to travel. With all the private flights though, the chances increase for airborne disasters. Seemed this happened after they landed. Glad that family and crew escaped a pretty intense moment. Kudo's to drivers knowing how to escape crashed shit on fire, right!