When you first control the WASP you will have to kill someone when they get to the drivers side of the truck. Then your team will be ready to breach. Before killing the two guys behind the gate on the ground, line the 1 guy on over watch above the water up with the two people on the ground in front of the gate so you can kill all 3 of them in one shot. Lower the WASP down to where you will shoot the guy on over watch in the head and the other 2 on the ground in the chest and it is a guaranteed Triple kill.
Credit to amyant3 for pointing this out.
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