OP when you saw the fire did you try to close the hood right away?
Opening the hood probably allowed more oxygen to fuel the fire .... it reminded of what happened to one of my tuna fishing ship ... there was a electrical wiring that that caused a fire in the engine room... the captain opened the engine room hatch when he should of closed that thing shut so no oxygen goes in.
2003 BMW 330i SOLD
2008 BMW 335i SOLD
2012 Mitsubishi Evolution X Current
2013 BMWX1 xDrive28i Current