Eternal Legendary/Crafted Item Crate

Near the camp of Jack and Joe, after climbing to the beginning of the bridge and running along it, near the building, under the bridge, a "skirmish" event with an orange icon appears. There are several bandits trying to open the box. The box is locked in the "very hard" level, and contains items of skillful and legendary level. Met only in this place, and this event appears almost every time when performing the above sequence of actions. Who knows what this event is? And where else can you find this?