2000 Expedition wheels locked up

Started to back out of garage and sounded like we hit a toy. Stopped and nothing there. Started again and wouldn't budge. Put in drive and moved about an inch and stopped. Jacked up right side and both wheels turn when in nuetral. Haven't checked left side yet. Any suggestions?

I had the same problem and it turned out to be the emergancy brake it had seized, Driver side had no pad and passenger side had seperated from the shoe. Good luck.