Interesting how when I reported about this happening to me that thread went

They purge your base, your chests get destroyed and drop a loot bag, that they then run in and grab it. With what is going on on PVP the official servers may actually be deserted by the end of summer; if it takes that long.

I set up better defenses on my undefended side and haven’t had it happen again. But server chatter says 2 others have gotten hit since me.