Absolutely amazing nobody was killed. I wonder what the conversation was like on the bus keeping folks in while there was fire encroaching. Even if you don't touch the conductors, potential gradient can ruin your day.
It can ruin your day if you walk towards or away from it, because your feet might bridge two areas of ground that have a 10kV difference. Your body being a bag of salty water makes a much better conductor than dirt, so the voltage takes the path of least resistance.
The safest advise is don't try to traverse the ground in that situation at all. However, if you must, the advice is to hop with your feet together or shuffle with very small steps (with the understanding that if you fall you're almost certainly going to fry).
A problem is that many people who use a bus are not physically capable of a leap. They may be elderly, disabled, pregnant or simply be very small children.
Doesn't smoke make air more conductive?