I think it would be best if you talk to them about a series of different emergency events, you need to make it fun for them and not scare them out of their wits.
Consider
1. A house / car / garden on fire
2. A car wreck
3. A person trapped in a hot car
4. A storm
Regarding a fire, if you and your child do find a fire then it could be a good learning experience for the child if you let them smash the glass on the fire alarm. But if they can not do it, then you will have to do it and show them. You number 1 task needs to be to raise the alarm followed by fighting the fire in a safe way.
_________________
Health is a state of physical, mental and social wellbeing and not merely the absence of disease or infirmity
I am not a jigsaw, I am a free man !
Diagnosed under the DSM5 rules with autism spectrum disorder, under DSM4 psychologist said would have been AS (299.80) but I suspect that I am somewhere between 299.80 and 299.00 (Autism) under DSM4.