I have a 1995 grand cherokee that wont start. Please help !!

So today when I was leaving work my jeep started up and ran just fine but when I was on the highway it shut off on me (like just stopped running). So I tried starting it up again and it started so I drove it down the highway about half a mile and it shut off again. So I sat there for a min and it started back up sounded like it was running rough and tried to get off the next exit to get off the highway and it shut off again but after it shut off it backfired twice. Now when I turn the key it wont start up it will try to start but will not run. Can someone please help me out as soon as possible. Please and thank you1