Rumsfeld: Flight 93 Shot Down

According to the official story, Flight 93, the fourth jetliner commandeered on 9/11/01, was flown into the ground near Shanksville, PA, as a result of a struggle in the cockpit between the hijackers and passengers who had rushed them in an attempt to gain control of the aircraft or otherwise prevent it from crashing into a strategic target, such as the U.S. Capitol.

So why does Donald Rumsfeld say that United Flight 93 was shot down?