There are always people at these border points in various lanes of traffic, but the risk would be less than if they got into the city of Cornwall and pulled into a school area or a mall where there were hundreds and hundreds of cars parked. That was our experience there at the time.
Some cars got past customs, or for whatever reason didn't stop. That's going to happen too, and there are things that can stop cars other than firearms, like gates, etc. But we did end up in some chases in the city of Cornwall, and people were hurt, children were hurt, and it was terrible. If we could have stopped a chase from coming off that bridge into the city, we would have preferred that.
But if you're going to do that, you have to be prepared to take aggressive action if you're faced with aggressive action. That's tough to do if you're not suitably equipped.