Huh?

Saudi Men Who Rode School Bus Arrested

Why did the bus driver even let them on?

Students on the bus became alarmed, as did the bus driver, who called ahead.

You stop the men as they are trying to board the bus, you ask them what they are doing, and you politely explain that the bus is for school children only. If they made an innocent mistake they will realize it and leave, if they are uncooperative, you call the police. You don't just drive on as if nothing happened and worry all the way to school what they are doing, possibly putting the kids in harms way. If you can't do that you shouldn't be driving a school bus.