1998 Buick Riviera trany sliped and grinding

I was driving about 30 40 mph and it sounded like my engine caught,this happend multipull times within about 100yds.I pull of to the side when the car would not move.Ingine accelerated,but nothing checked fluid,full and no flakes.Hop back into the car angry of corse and pushed gas bout halfway.It catches so I roll with it,on the way home There was a grinding sound coming from the transmssion and it was still sliping.is there any way it can be something other than the transmission itself. Thanks Chad
Strayer