Good question. If this play by play is accurate, I'd guess run.
1st and 10 at DEN 14:
(Shotgun) P.Manning Aborted. M.Ramirez FUMBLES at DEN 14, recovered by DEN-K.Moreno at DEN -8. K.Moreno tackled in End Zone, SAFETY (C.Avril). Penalty on DEN-P.Manning, Illegal Motion, declined.
Since it wasn't a sack I'd guess it was a run. Then again I've been wrong plenty of times before.