The Wampa scenes in Empire had Echo Base being attacked by the creatures but it was cut because they looked crappy. That's why there's a dead Tauntaun when Han gets on the Tauntaun to find Luke. Also, Leia references to it..."Then it couldn't have been one of those creatures"
They eventually locked the Wampas up and had a warning sticker on the door, which C-3PO rips off when the Snowtroopers invade the base. They enter the pen and the Wampas kill them.