Here’s why you always wait until the whistle is blown.
Canton (Michigan) Plymouth High learned that the hard way earlier this month.
The school thought it had defeated Westland (Michigan) John Glenn when it blocked a last-second field goal attempt. But when its players ran off the field in celebration, none of the players realized that the ball hadn’t crossed the line of scrimmage and was still in play.
No official had blown the ball dead.
So while Plymouth celebrated, John Glenn’s Tony Wilton alertly picked up the ball and ran 33-yards for the winning score. - from Yahoo.