This happened to me once. I killed all but one wearing no armor and wielding a stone sword. Twas an epic fight. Till the last one blew up as I was jumping away, launching me into a dark pit...
In the event something like this happens I laid out tnt underneath the floors of my primary building so that everything in a mile diameter would get blown up.
YOU CAN'T BLOW UP WHAT IS ALREADY BLOWN UP CAN YOU?!