Electrical Randomly shuts off

I have a 2001 Acura Integra, with 101,000 mi. I was driving last night and came to a stoplight, the headlights, radio, and dashboard lights shut off, but the car was still running. Also the maint. Required light came on for a brief sec. I made it home and this morning, pulled into the parking lot, shut off my car and the CD changer kept changing CD's and my horn went off for a brief second. I THINK it could be either my alternator or battery. But you all know more than me. Help! Thanks.