Overheated in my driveway...... cooling system questions???

[Dirtyjersey]

Hi guys, I own a 2004 x5 3.0 with 109k. Car was running for a few minutes after a trip to the supermarket. It was about 40 degrees outside. It overheated at some point and ran for likely about 1-5 mins after spewing coolant all over........ Upon inspection, the mechanical plastic fan disintegrated and threw pieces of plastic all over under the hood. It took out the fan shroud, plastic ps pulley, the coolant tank split........ I understand that the car had a lack of ability to cool with no fins on the fan, but my questions are as follows:

1. Why did the fan break this way?
2. Why didn't the electric fan come on and take care of everything?

I know the potential disaster of engine/head warpage, etc.....my fingers are crossed........