touchback or safety

Question
We have the ball on the opposing teams 5 yd. line and are attempting a pass for a touchdown. If the opposing team intercepts the pass in the back of the end zone and tries to run the ball out of the end zone to gain yardage but is tackled by a now offensive player turned defensive player before he gets out of the end zone is it a safety or a touchback?

Answer
It is my interpretation that it is a touchback. Now if the player who intercepted the ball, came out of the endzone, then for whatever reason went back into the endzone, that would be a safety.  Great question.  Please post it at my website coachfromthestands.com/forums and read my blog at coachfromthestands.com.   Coach B.