Smoke Detector Won't Stop Beeping

I was getting ready for work this morning when all of the sudden I hear this long continuous beep coming from my smoke alarm. I opened it up, there were no batteries, and it was still making this noise. So I thought that maybe there could be a back up battery or something, so I unhooked it and disconnected it entirely, but it still was making the noise! It seemed to be coming from the ceiling. And it's still doing it as I type! Can some one help me figure out how to stop this before I go absolutely insane?

By LET