What you have to do is you have to shoot the electric things at the top and then all you have to do is jump over. But be careful because it is quite hard to jump over. Get your timing perfect.
Once you start the Second Generation you can just slip through the fences. The Second Generation is when you are playing as the child of the original main character.
You can first shoot the Sniper from behind the truck or rock by jumping up and down. Once he is killed, shoot with the pistol at the side of the rear side of the barrel and it will create ripples and...