After the helicopter blows up the bridge and you get back up onto the flat part of it, you will see a truck full of soldiers backing up away from you. While the truck is still moving, a soldier jumps out the passenger side door. Shoot him and he will drop the M60E4. You will have to throw a grenade almost immediately. There will be four soldiers that will run out of the back of the truck that you must kill. Note: If you run past the location where the truck stops you will immediately die.