1. Insurance Claims. Just about the first thing you should do once you know everyone is safe is call your insurance company. You need to file a claim as soon as possible so they can get you the money you will need to get everything back to normal. This should always be one of the first things that you do after disaster strikes.
2. Carpets. If you have carpets in your rental property, you may want to consider ripping them out and replacing them. This is true whether you had a fire or a flood. In the case of a fire, it is the easiest way to get the rest of the soot and dirt out. In the case of a flood, it is the best way to make sure mold doesn't start to grow in your floors. Even if you think the carpets have dried, you may still develop mold down the road, so think about this one carefully.
3. Take Some Time. You may need to take some time to process everything. If this is a possibility, then do so. There is nothing wrong with taking a little bit of time to get everything in order before you start to rebuild.
4. Remodel. Depending on how severe the damage was, you may have to rebuild parts of your property anyway. This is a perfect reason to do any remodeling work that you may have been tossing around. Redo that bathroom you had been looking at, knock out that odd wall in the basement, get a new color of paint. It makes more sense to do it now as opposed to redoing exactly what you had and changing things around later.
While things like floods and fires are life changing and may cause an extreme amount of damage, they don't have to be considered all bad. As long as everyone make it out okay, most things can be replaced. Remember to try and look at the positive side of things and work towards making everything better than it was before.