If you have time to plan, you can take quite a bit more than 5 things, but katlaughing's recommendations are good too.

But the main thing is to get out, even if it has to be on foot. You can't control for factors like "no keys!" or loading the car, only to have something crash down on it. That is the gods telling you in no uncertain terms to MOVE OUT NOW! I've had a number of personal fire horror stories in places I've lived over the years, though I've never been burned out of a place. We have taken in people who have lost everything though, including cats, dogs, fish, and horses.

I just recently learned that you can easily transport cats safely in pillowcases that are closed up.