[Travis McGee]

I see your point about multiple fires stopping one another, I am seeing a single massive fire started on one line by multiple terrorists at the same time, so it would be more like a single battle front advancing, not multiple fires crossing paths.

[RightWhale]

Sure, it is possible and I get the picture, but fires are notoriously undisciplined. They wouldn't maintain ranks for long. A city firestorm like Dresden or Tokyo would be unlikely. Just one factor: wind direction and intensity changes constantly and isn't normally uniform to begin with on that scale.