What must a school bus driver do to secure the bus when unloading students at the school, that is NOT part of the on-route unloading procedure?

AAMVA CDL Manual, Section 10.2.3 'Unloading Procedures on the Route,' p. 10-4, and Section 10.2.4 'Unloading Procedures at School,' p. 10-5; 49 CFR Part 380, Appendix D, Unit D1.2 (Loading and Unloading)

Unloading at school typically involves a longer stop with the driver potentially leaving the seat to supervise, so the manual requires fully securing the bus (ignition off, key removed) rather than just holding the brake as on a quick route stop. This prevents an unattended bus with the engine running and keys available from becoming its own hazard while students are exiting nearby.