Raid by Guerilla Forces
Word of your relative success as a farmer has spread through the local community. Perhaps this is the reason that a group of heavily armed guerillas pay you a visit and rob you of most of what you have, at the threat of your lives.
Note: Supporting a representative is a way of ensuring fewer guerillas will be around.
This event is more likely to appear when the player is performing well in the game.
WikiPedia articles on Guerilla Warfare:
“Generals, Guerrillas, Drugs, and Third World War-Making,“ article by Michael K. Steinberg in Geographical Review Vol. 90, No. 2 (Apr., 2000), pp. 260-267 (8 pages).