New in v0.7.7.3
Gangs will form near towns with low stability and grow in size. The lower the stability, the faster gangs will grow. Keep stability above 50% to avoid gangs. When the resistance controls the town, your Police and gangs will fight whether you are around or not, so it pays to place a Police Station in towns to raise stability and therefore get more taxes.
Gangs are based out of a camp nearby to the town, most likely hidden deep in forests and jungles. At that camp or nearby you will find their leader, he must be eliminated in order to disband the gang. If support in the town is high, the citizens there may notify you of the camp's position and mark it on your map.
Each gang member killed will raise the stability of the town slightly. However each police officer that is killed will drop stability. When the town is out of spawn distance (ie you are not there), these battles will be simulated and the corresponding stability changes applied.
Gang members pay $50 to the player who killed them, including if they are killed by your AI recruit/squad. Gang leaders pay $200.
When the leader of a gang is killed, that gang will disband and no gang can be formed in that town for 1 hour (real-time). The town will also get a large boost in stability.