The OP describes an ugly scene handled well.

Racers do not have to be a problem.

The are fortunate around here in that the top racing top is lead by a rider and trainer who is also a bike safety fanatic. The attitude seems to be catching. I see many fast riders and pace lines riding smart on local trails, hitting it hard when the way is open and shutting down when congestion or other conditions make it wise. This gives racer wannabes an excellent example.