Keeping in mind that you should always use common sense and spending the small amount of time to wait for children to cross is always safest, I'm curious what the law says.

If there's a school bus stopped with flashing lights etc. at an intersection, and I am crossing in front of it perpendicularly on the intersecting street (i.e. if the bus is going east-west, and I'm north-south), am I required to stop?

From what I've read of the law, it's quite clear about cars approaching from behind or towards the bus, but is less clear about cross-traffic.

Thanks in advance!

It's legal, although not usually practical considering the potential for foot traffic.

The laws regarding school buses always use the term "when meeting" for vehicles travelling in the opposite direction or "when approaching" for drivers coming from the rear.

Your vehicles never "meet," therefore it's legal.

Ontario's Highway Traffic Act Section 175, (9), FORBIDS a school bus from activating it's overhead red signal-lights at:

~ an intersection controlled by traffic signals;

~ at a stop sign;

~ near a crosswalk;

~ at school bus loading zones.