At mine, on that day, they started it by announcing over the intercom one morning that a popular classmate had been killed by a drunk driver on the way into school. Even though it should have been obvious that's not how it would really have been handled, it got the shock it was intended to get. A few people even ran out of classrooms crying. That was before everyone had cell phones.
I guess they wanted to make a point about the fatality rate statistic, too, though, so they kept going, announcing another person every however many minutes. It immediately became really obvious to everyone what was going on when they announced the second person. I think it lost more of its desired effect the more they continued.