Ignition switch stuck in run position??

I have a 93 GMC Sierra 4x4 and when I started it up today it started OK but I couldn't get it into gear. I tried to shut it off but now I can't turn the key back from the run position so I've been shifting the column shift back and forth and I finally got it to shift into gear but I still can't shut the damn thing off so it's sitting in my driveway right now running. Anyone have any idea of what is causing my ignition to be stuck in the run position? :banghead: Thanks for any help.

I fixed it, I had to remove the steering wheel and replace the lock cylinder.