Air Bag Light Started Flashing and Car Cut Out

I was driving my car home from work today and it started acting weird. The air bag light started flashing, the speedometer started jumping in sync with my turn signal and the car started to lose power. Eventually it completely died. I tried to start it back up and it cranked a little but it wouldn't start and acted like the battery was almost dead. I let it sit for about 20 mins and was about to jump start it but then I tried it again and it worked fine. Any ideas what might be causing it? I've had the car for a while and never had any problems like that. Thanks in advance!