How do you beat level 3 casualty

This is how you beat level 3!! You make the dude in the tower shine his light on the dude on the ground. He runs, knocks over a barrel, then runs the other way.
Click the barrel he's running at so it squashes him. then as soon as the car thing comes in, wait for the gate to just open, and click the lever plug thing. the car should run into the barrel and blow up. Then, click the dude with the gun... Click the boxes, and they all die.