5 foot 1 inch hole in airplane while in flight

http://www.cnn.com/2011/TRAVEL/04/03/arizona.flight.diverted/index.html?hpt=T1
 An airplane going to California from Arizona was flying over arizona an all the sudden a huge hole tore in the top of the airplane.People were terrified and the plane dropped 11000 feet in a nose dive but the pilot regained control and landed in a near by military base. The boeing aircraft is now under investigation as to what may have caused thids hole.