School Bus lights

Buses use signs and orange flashing wigwag lights to warn you that they are picking up or setting down school children. The lights begin to flash when the bus stops and the doors are opened. They keep flashing for about 30 seconds after the doors close and continue even after the bus moves off. You must not drive past the bus in the same direction at more than 40 km/h while the lights are flashing as there may be children crossing or about to cross the road.

Additionally

Flashing Headlights

When buses are dropping off or picking up school children the driver may flash their headlights at you indicating children are crossing or about to cross the road.
The children may not be aware of you from where they are standing.