School Bus Watch: Anti-Terrorism Training for School Bus Drivers advises school bus drivers to be alert for:
U Vehicles following the bus.
U People carefully observing or photographing a bridge, chemical or power plant or government building.
U Unusual inquiries about the bus route.
U Abandoned vehicles or packages.
U Unfamiliar delivery vehicles near a bus stop, school or bus garage.
U Strangers loitering at or near the bus stop; if a driver sees a loiterer, he should keep the children on the bus and call the dispatcher for instructions.
Source: Program officials