Article in English: Most stings occur when people accidentally step into or sit on a fire ant mound, disturbing hundreds of thousands of fire ants primed to defend their home. If you start feeling stings, the first thing to do is get up and leave the area as quickly as possible. Fire ants clamp onto the body with their mandibles and are difficult to remove. Quickly rub them off with your hand or a rag.  Jumping into water or running the ants under a spigot will not remove them if they have already clamped down with their mandibles.  If there's a chance more ants have gotten into your clothes, remove them immediately.

Summary in Vietnamese:
Tránh khỏi tổ kiến lửa. Giũ kiến.