I went to jump start my wife's 98 buick regal. I checked the cables to insure they were on correctlly. When I turned the ignition, they were a loud bang the plastic cover over the plugs, (Cover shows type engine. 3800 V6 series 2) exploded into pices, the oil cap and neck that the cap goes into blew out, and caused fire on the wiring near the windshield. Any ideas?

That doesn't sound right at all. What was the vehicle doing prior to it needing a jump start? What shape is the battery in?

That doesn't sound right at all. What was the vehicle doing prior to it needing a jump start? What shape is the battery in?
The battery had a dead cell from what I could tell. If the cables were backwards would that have caused all this havok.

If the cables were backwards, then you probably blew up the battery and possibly shorted out the electrical system. Did you connect red to positive and black to negative? Was your wife having any other problems prior to the vehicle not starting?