Transportation Security Administration: within the surface transportation systems, TSA’s primary security focus is in oversight, cooperation, and regulation. TSA works collaboratively with surface transportation operators, local, state and federal security partners to ensure appropriate security postures are employed. Along with industry partners, TSA safeguards all four general modes of land-based transportation: mass transit, freight rail, highway motor carrier and pipeline; and supports in maritime security efforts.
Highway and Motor Coach Security training courses and material include a focus on school buses. The link can be found here: https://www.tsa.gov/for-industry/surface-transportation#quickset-surface_transportation__1