No! I would not be allowed to, as I have various health problems but I admire the people who do work as volunteer firemen enormously. In Germany, we used to make a monthly donation to our local fire station, as a fire in the house in one of my top dreads. I was also amused by the fact that they were universally known as "Free Willies" which was the local dialect version of volunteer.... (The German word is actually "Freiwillige".)
Yes, I had to. In the summer I went to work one morning and saw smoke coming from the roof. I immediately sprang into action to join my coworkers who were trying to get the flames under control. We salvaged what we could.
The fire truck was called. Even they had a problem putting out the blaze.
I hope never to have to go through that again.