Glass just broke!!!?

i was on the computer when suddenly i hear a ‘BANG’
and i look up and I saw that the whole front of my oven
(which is made of glass) was broken!!

It happened so fast and all the glass is broken.
how and why did it happen? is it some kind of pressure?

oh by the way it wasnt on. it was turned off since last night..

hmmm… heres a pic

http://i184.photobucket.com/albums/x105/…