As I recall (and if I'm thinking about the same spot as you - you turn north round a corner and there's four of them waiting for you) then what I did was this;
Station one of my characters at the far end of the corridor. Send the other one (the one with better speed) very very slowly up the corridor to attract attention. You should only get one to follow you like this. Then lead it back to the other character. And blast it with missile weapons or magic as much as possible, because if you close to melee it will just lead you back to it's companions, so you want it to stay up your end of the corridor, and only melee it when you'll kill it with one good stroke.
Oh yeah, and heavy use of the space bar to allow refreshing health/mana with potions. I was balsting it with magic with two character that had pretty mcuh no mana at the time.