Stuck by the D-Gun thing

[jsk663]

I really need help. Im stuck in the part where your in front of this metal gate, behind it is a church/muesuem looking thing and a "Suppressor" cannon which fires deadly disintergrating laser/artillery rounds. I can't get past it and I don't know how to destroy it. Help!

Here's a screenshot

 

[Vegeta897]

Keep looking around. You will find the way.

(You can't destroy it)

If you find it too difficult to get past it without getting killed, turn on God mode...

 

[Analogy]

In a rather anticlimactic turn of map design, there's a door far to your right (in that screenshot) that you can go through to get around the forcefields.