https://www.ontario.ca/document/off...book/dealing-particular-situations#section-10
Reacting to an approaching emergency
When an emergency vehicle is approaching your vehicle from any direction with its flashing red or red and blue lights, or siren or bell sounding, you are required to bring your vehicle to an immediate stop.
When bringing your vehicle to a stop, you are required to bring your vehicle as near as is practical to the right-hand curb or edge of the roadway. When on a one-way road or divided highway having more than two lanes of traffic, move to the closest curb or edge of the roadway. Your vehicle should be parallel to the roadway and clear of any intersections, including highway on/off ramps. Do not move onto or stop on the shoulder of the roadway, as emergency vehicles may be travelling along it.
Use extreme caution when stopping your vehicle because other drivers may not yet be aware of or are already reacting to the approaching emergency vehicle. Look to the front, both sides and toward the rear of your vehicle, signal your intention to pull over well in advance and begin to adjust your vehicle's speed to merge with any traffic to the side you are pulling to. Once you have moved your vehicle to the side, brake gradually as required and bring your vehicle to a safe stop. Avoid any sudden changes in direction or excessive braking and be aware of any vehicles approaching fast to the rear of your vehicle.
If you are in an intersection and preparing to make a turn when an emergency vehicle is approaching, you should abandon the turn and clear the intersection by proceeding straight when safe to do so, then pull to the right and stop. This will clear the intersection and minimize the possibility of a collision with the emergency vehicle should it be passing you on the side you intended to turn towards.
When the emergency vehicle has passed, check to make sure the way is clear and signal before merging back into traffic. Remain vigilant for additional emergency vehicles, and remember it is illegal to follow within 150 metres of a fire vehicle responding to an alarm.
Note: Some firefighters and volunteer medical responders may display a flashing green light when using their own vehicles to respond to a fire or medical emergency. Please yield the right-of-way to help them respond to an emergency call quickly and safely.
Police or other enforcement officers may require you to pull over and bring your vehicle to an immediate stop. Typically, the officer may signal this requirement by driving their vehicle with its emergency lights flashing and/or siren on behind your vehicle or by using hand gestures from the side of the road. When stopping your vehicle, follow the previous procedures, except that you should bring your vehicle to a stop outside of traffic lanes and onto the shoulder of the roadway where possible, or turn and stop on a side street with less traffic if in the immediate vicinity. If the officer gives direction as to where to stop, follow the officer's directions.
Stay alert
When you see an approaching emergency vehicle with its lights or siren on, prepare to clear the way.
- React quickly but calmly. Don't slam on the brakes or pull over suddenly. Use your signals to alert other drivers you intend to pull over.
- Check your rearview mirrors. Look in front and on both sides of your vehicle. Allow other vehicles to also pull over. Pull to the right and gradually come to a stop.
- Wait for the emergency vehicle to pass and watch for other emergency vehicles that may be responding to the same call. Check to make sure the way is clear and signal before merging back into traffic.
- Don't drive on or block the shoulder on freeways. Emergency vehicles will use the shoulder of the road if all lanes are blocked.