After a crash, the bus is resting on an unstable embankment where its position could shift and increase the danger to the occupants. This situation matches which mandatory evacuation trigger from the AAMVA CDL Manual?

AAMVA CDL Manual, Section 10.3.1 – Planning for Emergencies (Mandatory Evacuations), p. 10-6

A bus that could slide, roll, or tip further is not a stable place to keep students while waiting for help. The manual treats an unstable position as grounds for immediate evacuation precisely because waiting could make things worse.