Looking at the aerial footage you can see the two retardant drops clearly with the second directly behind the crash site. Looks like it may be exactly what the video earlier was talking about target fixation and they clipped the shallow ridge directly after the second drop, and slid to a stop. It does look very much like they were trying to tag the second drop onto the first line to form a break. Considering this seems to be a very common form of aerial firefighting mishap I wonder if they can mitigate it by adding another non flying crew member to monitor the drop while the pilots focus on flying and terrain, seems like if both pilots are watching the drop it's easy to forget whats ahead of you.
BTW I'm not saying this is exactly what happened but it fits pretty well with what the earlier video was talking about.