Just jumping in here for a moment. First I wasn't at WDW when this fire occurred so this is just my opinion from being in the fire service for over 30 years. The fire appears to have been involving some very flammable material and with the wind being what is was caused a quick spread. Now, there were comments of the fire not being called in quickly I'm sure 911 was getting calls as soon as the fire was spotted. The apparatus needed to respond have to go to areas that allow them access to the parks and as you can see in the one picture the firefighters are guiding the operator of the aerial platform through the park. Just driving a rig like that on open roads is a task in itself take it from me let alone drive it in any of the parks at WDW. I have visited the brothers at Reedy Creek Fire Services and these guys and girls are the best at what they do and what they respond to day after day I tip my hat to them. Now, getting back to the fire, once a fire is discover you must evacuate the ride for everyone's safety from the pictures I was looking at there was not enough fire to cause any type of collapse but I'm sure caused significant damage. As for extinguishment, it appears that the aerial was used primarily so the brothers did not stretch any hose but, they may have after the fire was knocked down. I can't recall if the aerial platform has an onboard water tank. If so it would be around 300 gallomns which would be more than enough to put out this fire. Tey would also have to tie into a hydrant for water supply so not sure how close a hydrant was. That being said the firefighters ay Reedy Creek are always busy as the day we visited with my sons there was only one member available for the tour. For more information on RCFD here is their link.
http://www.reedycreek.org/index.cfm?Section=10&PageNum=78