Question

Once you have stopped for a school bus, do not pass until the driver signals you to proceed, the red lights stop flashing,

Answer 1

Once you have stopped for a school bus, do not pass until the driver signals you to proceed, the red lights stop flashing, or the bus starts moving ahead. Whenever a vehicle ahead of you stops to let  a pedestrian pass in front of you, you should stay in line and until the vehicle ahead proceeds.