Campaign Achievement - Alive Inside!

So i've been working on the campaign achievements and i've been doing fine up until this one, which doesn't seem difficult at all, but i scanned just about the entire map and only came up with 17/22 Moebius Survivors.
The Initial 4 Marines.
Goliath / 2 Marines.
Goliath / 2 Marines.
2 Marauders / 2 Marines.
Goliath / 2 Marines.

Has anyone finished this that can help me find the other 5. Thanks in advance.

 

One of the survivor groups says they saw movement over at ____'s Guns.

If you go to one of the roofs a bit to the south about five marines will spawn out of the roof access.

Have fun.

[edit]
I think it is just before the last tower to be destroyed.