2000 Mustang Automatic: Transmission stuck in first gear!

I've had my v6 for about 3 years now and this is the first inkling of any transmission problem I've had. I was driving home the other night when I got off the highway and slowed down to drop off a friend. I attempted to put the car in park, but the shifter decided to move freely between every setting. It clicked into place a few times, but did not change gear or shift into park. After that I drove back to my house, but the engine was revving high as the car would not shift out of low gear. I was able to maneuver the car into a safe spot (since I couldn't go into reverse to parallel park) and ended up pulling the emergency brake to secure it before turning it off. The car doesn't turn on now because it's not in park. The shifter still moves freely between all the settings and will occasionally click into place, but does nothing. Is this a cable issue that can be fixed if I just tow to my mechanic or do I have something more serious on my hands? I've never encountered this before, so any help or advice is welcome! For now it's just sitting there, mocking me. Thank you in advance!