The shocking incident was filmed and uploaded onto YouTube but is too graphic to be published.
It shows a vicious 25-strong mob cheering on as the bloodied girl is punched and kicked before being doused by petrol.
According to reports the unnamed girl was allegedly involved in a gang that murdered a motorcycle taxi driver.
The victim and two other men apparently shot Caros Enrique Gonzale Noriega, 68, before robbing him and running away.
Her teen accomplices escaped down an alley but the girl took a wrong turn and found herself trapped by a vigilante mob.