Being the unofficial dept. photographer for my volunteer dept, I hasome experience in this. I don't really shoot on scene anymore (we're understaffed, so it's all hands on deck when we get a call, the photos are less important than preservation of life and property obviously). The best answer I can give you, is use the scene lights to your advantage. At night, there will most likely be honda lights running all over the place, the scene lights on the trucks will be on, and the light towers will be up (if the trucks are equipped with them). You have to look and see where there is light, and use it to your advantage. Also, you can avoid catching the reflective strips with flash by getting your flash off camera. It's all about angles with light, and if the flash is angled so that it doesn't bounce light off of the subject and directly at your camera, you won't get as much reflection from the strips.
My question for you is; what type of camera are you using? Equipped with something good in low light, and a fast, professional lens, you could easily shoot most fire scenes with just the ambient light from the fire. You'd need something great at high iso's though, at least a Nikon D7000, and preferably a D700. Or the D3s, which would be the absolute best camera money could buy for low light. As far as lenses, fast primes are your friend. On a budget, a 50 1.8 will do the trick for around $100. Even a 2.8 zoom is going to be pretty slow for shooting with this small an amount of light. Something like an 85 1.4 would be ideal. This is one of the few types of photography where having the proper equipment really is essential, and the right equipment isn't cheap.
However, it can be done with a lesser camera, you just need to get a bit creative with it, and use a tripod. These were taken a few years ago, before I really knew much about photography. Used my D40 on a tripod with a 50 1.8.
EDIT: I'd post some newer examples of my work, however per dept. regulations I'm not allowed to. The only reason I can post the ones above is that they were taken before I was officially a member of the dept. and therefore I, not the dept, owns the rights to them. Beyond that due to legal and financial issues, my dept. prohibits me from using my own camera gear on calls because we aren't allowed to take copies of the photos home without approval through our commisioners, blah blah blah, I hate the politics behind it all, but I love being in the fire service.