When I was a Fire Science Student, I did a paper on "Conflagration's." In doing research for that paper, I came across and article about the spread of fires in narrow canyons, where the close proximity of narrow canyons was leading to fires jumping from one side of canyons to the other side, and how this could happen in areas where high rise buildings were built too close to each other. Perhaps this is what is going on in Hong Kong?
Also, it reminds me of London's Granfield (Spelling?) Tower disaster. The indication for the FDNY is that we need a few High Ladder or High Tower Ladder units in FDNY capable to reach the 20th story or so in case of a major fire in one of the now numerous "Sliver" high rise buildings as well as the many traditional High-Rise buildings, exterior streams are available. Captain Bob Rainey FDNY Engine 26 retired