Attacking the Shelter, you can get up to two Сhests: one guaranteed and another one if you have a Horse. The attacker gets the items from the Сhests he selected and looted. Meanwhile, the defender loses the items available for the loot from the Shelter. But the total value of the lost defender's items and the acquired attacker’s items should match.
N.B. During PVP raids, you can loot any item, except for those held in the Waggon and the ones equipped on the character.