At approximately 1:35 am the belt crew was moving belt when they heard a roof fall. Supervisor immediately went to the last open x-cut in #8 entry at #23 x-cut of 12th West section and found a roof fall 20' x 20' x 4.5' high. The area was dangered off and called to the shift foreman. Shift foreman notified superintendent and safety supervisor. Not above 5' bolts being used.