It sounds like a squib - primer blew the bullet part way into the barrel, but it is still stuck in the casing, too.
If you can field strip it, skip ahead, if not:
If you can, gently pry the extractor up off the case, or partially disassemble the extractor to do the same. Then you'll be able to open the slide or field strip the gun. REMEMBER NOT TO PULL THE TRIGGER FOR DISASSEMBLY IF THERE IS ANY CHANCE OF THE ROUND GOING OFF.
After the barrel is out it souldn't be to difficult to pull out the casing with pliers and then get a good look at the the stuck bullet to tap it out with a dowel.
Good luck, be safe.