2001 Cadillac Deville wont start

I have a 2001 Cadillac Deville with the 4.6 northstar
V8. I started it and drove it around perfectly fine
this morning. I checked the oil before I was going
to go out for dinner but the car wouldnt start. I
have no dash lights on in the on position other than
the check engine. I can hear a clicking behind me
from the fuse box when I try to turn it over but
nothing else. Ive tried boosting, and changing a
few fuses but same thing. Could this be anti theft
system or something else? And how would I fix it?