Welcome to the forum! Where are you from? I have never heard of CFR, but I guessed right at it being Certified First Responder. I hear it more often as Emergency Medical Responder.
About Fire hiring, it varies by department in so many ways. Some require nothing at all, some require Fire certifications, and some require EMT or even Paramedic for certain positions, let alone experience. Fire is a diverse community, and it seems the more diverse your resume is the more likely you are to be picked up.
I'm not sure about certification, but I know you cannot be licensed in Texas as an EMR (let alone EMT and up) unless you are 18. You can take courses (depending on the school's policy) and even test, but you can't receive licensure until you are a legal adult. Even if that varied by state, it would be in a company's best interest to not hire minors for such a position, simply due to liability and the overcomplication of it all.
I took my EMT course the summer after my senior year in HS, and I was 18. That said, one of my classmates who was a year behind me in HS was also in the class, despite not having her diploma or being 18 (surpassing school policy), so obviously some schools will work things out. She still could not be licensed until she was 18 though.
Get your CPR if you haven't already, and maybe even consider CPR Instructor if you are able. Gives you something to do. Take a look at any volunteer departments or teams in your area, as they may be more lax on the whole minor/adult issue, or enough so to at least teach you something.