Penalty with time run out

[drinkeii]

Hi - I am a basketball/swimming/soccer official, and am running an intramural program at my school. I ran into a problem with a flag football game, and would like to know what the regular football rules would say about this situation: (our flag rules don't cover this one )

Ball is on the four yard line, 3rd and goal. The clock had about 4 seconds left on it when the ball was snapped. It ran out during the play, but before the penalty occurred. The score was 32-38, with the lower score team attempting to score. There was an offensive penalty in the endzone (an illegal push, which by our rules, is a 5 yard penalty + down over), but the ball was caught by another player. The other team accepted the penalty. What occurs from here? Do we have one more play 5 yards back, or is the game over because the clock ran out. I assume if they declined, it would have just been the TD, with an extra point attempt, and I could handle it from there according to our rules.

Help!!

Thanks!