Originally Posted by D20SRD
Crowds
Urban streets are often full of people going about their daily lives. In most cases, it isn’t necessary to put every 1st-level commoner on the map when a fight breaks out on the city’s main thoroughfare. Instead just indicate which squares on the map contain crowds. If crowds see something obviously dangerous, they’ll move away at 30 feet per round at initiative count 0. It takes 2 squares of movement to enter a square with crowds. The crowds provide cover for anyone who does so, enabling a Hide check and providing a bonus to Armor Class and on Reflex saves.
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 whom the crowd listens to. The crowd ignores everyone if none of the characters’ check results beat the DCs given above.