Good Morning!
This is a sollution from my STAR WARS (D6)-days (it helps to have many d6 handy...) :
Each combat round, we rolled 1d6 for each Non-PC-Participant. A '1' for a 'Dad Guy' meant, he took out a 'Good Guy' (low is bad for the players...), a '6' for a 'Good Guy' meant, he took out a 'Bad Guy' (high is good for the players).
To keep this even simpler, you could use one number for all of them. Or use another type of Die-Roll (12 on 2d6, if you want an ever-lasting combat...) for variations. A highly trained combatant would perhaps have a better to-hit chance (say 5 or 6 on 1d6), but that might be too complicated again - the idea was to keep the action running fast...
A 'taken out' combatant didn't necessarily mean a dead combatant, just not combat-ready any more.
Have a nice day,
Aldan Romar