2000 Pontiac Grand Prix electrical system problems

Husband moved the 2000 pontiac grand prix gtp w/ super charger. Closer to work site & parked the car, sat & ate lunch in car. The cabin of the car filled with smoke. Husband couldn't get doors open, but got the windows to come down. Had to crawl out of the windows and realized car was on fire. Within 10-15 minutes the car was completely in flames. The firemen had to pry the sides of the hood up to get the fire out. The car was totaled. Approximate mileage 121000.

Drove car for about 45 minutes on freeway then parked in a bank parking lot. Turned car off and went into bank. All indications on dash where fine that day and car drove just fine. About 15 minutes later, some one came into the office I was at and asked if anyone in here has a black grand prix. I went out and found that black smoke and fire was coming out of the engine compartment on the passengers' side. The fire department had already been called. Car then tried to start itself.