My house alarm just started beeping and I have no idea how to shut it off?

Okay so my parents are gone on a vacation (cell phones are off, ive already tried calling) and we have this house alarm that we have never used before and I just went upstairs and it keeps going "beep beep .... beep beep" and so on. We've never used the thing so I dont know the code for it. The only on that is lit up on it is "TBL" which i have NO idea what it stands for. And also the "ready" light is on. It's made by Paradox if that helps? What's going on?!? Please help!!