I've been on both ends of that -- as a student and as a teacher. In both cases, the death was a suicide and thus only a single person, but that doesn't make it any easier. Take it easy on them, and don't dwell on your last moments with him. I may not know exactly what happened, but I seriously doubt you made him angry and that rage led to the accident...I know you'll think that at some point no matter how likely or unlikely it was, and that isn't healthy. While sometimes teachers can be there to prevent things from happening, a teacher who cares will seldom cause anything like that.
Just do your best to be supportive of your students tomorrow, and hope the weekend can wash the hurt away and you can get back to business. Honestly, in most regards, the best thing you can do is to continue teaching. Certainly on the days after the news hits, if not necessarily the day of. Anything to put their minds in a different place is a good thing.