First kill all the people around you, then kill the 2 snipers in the field, after go to the pieled up red and white car then jump on top of the bumper of the white car.

Then hop on the hood and after that run jump onto the roof of the red car, facing upward.

Then hop onto the orange cargo box, after that jump on the white car toward the right, then hop through the hedge.

Start going toward the right, then you'll come across a building. Go up the stairs to the first window then jump out the window.

Note radiation still kills you.