Instructions
Hide behind any crate or other large object while Navarro and the other soldiers fire -- press the Circle button to hide -- and wait until Navarro leaves to reload.
Shoot and kill the remaining soldiers once Navarro leaves, using the L1-R1 button combo. Run and go after Navarro after the guards are dead.
Avoid the falling crates as you chase Navarro; look for the warning prompt in the screen's bottom left corner and press the Circle button to dodge. Follow Navarro up the stairs.
Hide behind the first set of boxes during Navarro's first round of fire and then roll over to the second set using the Circle button as he reloads. Repeat this for the third set of boxes during the second reload.
Run and hit Navarro directly as he reloads for the third time to trigger a quick-time event. Watch for the on-screen prompts and hit the buttons they tell you to in order to knock the gun away. Navarro will push you back and go for the gun.
Hit Navarro again quickly before he gets the gun and repeat the same quick-time process to defeat him for good.