The combat rules are used as a simple abstraction of reality, not a substitution nor an all encompassing representation of reality.
When combat spontaneously combusts it is an opportunity for common sense and and judgment to be made.
There should not be rules for everything. If there were, it would be no better than playing a simple computer game.
|King of Vrock|
If the creatures are noncombatants treat them as squares of crowds.
Directing Crowds: It takes a DC 15 Diplomacy check or DC 20 Intimidate check to convince a crowd to move in a particular direction, and the crowd must be able to hear or see the character making the attempt. It takes a full-round action to make the Diplomacy check, but only a free action to make the Intimidate check.
If two or more characters are trying to direct a crowd in different directions, they make opposed Diplomacy or Intimidate checks to determine to whom the crowd listens. The crowd ignores everyone if none of the characters' check results beat the DCs given above.
--Vrock Party Weekend