Tips on how to save your friends on the concentration camp attack

Having no casualties on your side is tricky to achieve and there's no way to guarantee this as far as I know.

Here's how I did it

You don't want to attack head on. Don't go near your teammates as it will initiate their assualt. Instead go into the camp from behind. You can get far into the camp from there without the bandits attacking you.

Once you're there run on the left side until you reach the chopper near them. Run forward on the right side of it to the bus. If you run past the chopper on the left side the bandit with the shotgun will most likely kill you. Get the mentioned bandit and run to the left side again. Here you have a good shot at shooting bandits as you pass vehicles after vehicles until you reach the front. Do your own thing from there. It is important to deny the enemy from using their sniper grenade on your friends if you want to save your mates. If you have a sniper rifle you could see if saving them is easier using it. I haven't tried it.

Once all the bandits are dead, check the proximity counter. If the number is 10 then you know you have succeeded as there are 5 liberators and 5 slaves. It would be wise to save your game now. But hold on, you're not in the clear yet. There are bandits coming out from the "north-west". Get them before they start a firefight with the others.