What should you do when the fire alarm rings during your presentation?

Jason writes:

About eight minutes into my breakfast presentation to the local chamber of commerce at a fancy restaurant the fire alarm rang. The alarm was annoyingly loud so naturally I stopped speaking and forced a smile.
You can imagine my first thoughts. They were angry selfish thoughts. Why now? Why me? However I did not convey those thoughts on my face.

But the whole blog post is full of ideas, so that if it happens to you, you will be prepared. Read it here