Car won't start, no headlights, dashboard lights, clicking, nothing.

I've not been having any problem with my car until today. I tried to start my car this morning and when I turned the key nothing happened. At all. No clicking, no lights, nothing. Even with a booster the most we could get it to do is turn the interior lights on for a second and then when I tried to start the car I got one click and it went dead again. Is this a REALLY dead battery or maybe alternator? Car is a 1999 Buick Century via /r/cars http://ift.tt/2usW5zv