Gonzaga/St. Mary's Ending

[WhistlesAndStripes]

Anyone see it? Here's what happened:

St. Mary's is up 5, and gets a rebound with about 10 seconds to go. They get the ball up court and dump it in for a dunk. Clock stops with 1 second left, and St. Mary's now has a 7 point lead. Fans storm the court. Gonzaga players and coach head off the floor. Officials are blowing their whistles. It takes a couple minutes, but finally the PA Announcer gets everyone to clear the court. Out comes Gonzaga. Technical foul is assessed against the crowd. Gonzaga player hits both FTs. Ball is given to St. Mary's for a throw in. Clock expires. Fans rush the court again.

Why did the officials feel this was necessary? Seemed rather silly to me.