How to pronounce “first sergeant” in English

And they're still yelling outside in the hallway, then out of nowhere I hear "Why is there only one person outside of this door!" Then BOOM, I hear my door fly open, slam the back wall,chip is like, paint its, paint chips are like falling off the door. And then my first Sergeant, who is the 17-18-year-old, comes in and he's yelling and he's screaming at me and he'scursing at me and he spitting on the back of my head and I'm sitting there and laying in my bed trying to get some sleep.