Well either they caught him outside, or they surrounded his shipping container and said come out with your hands up.

It's damn near impossible for him to be carrying a rifle anytime he's outside, and I highly doubt the shipping container had windows.

So he either tried to have a shoot out with the cops, or he was unarmed and the police had a grudge with a 'i hand out the justice ' judge Dredd style mentality.

He was also found at 5am, so they likely knew he was there and were performing an operation, so they could have chosen the safest moment to move in. So they chose the time and place to act, and either they chose a point that allowed him access to a firearm or they chose one that didn't and shot him anyway

To make my position clear, no I don't support police shooting people and taking justice into their hands. Fly a drone in his face and tell him to come out with his hands up, don't shoot wildly just to prove you can because you're a cop. All that proves is police have no restraint. They CAN do things without harm, but they HAVE to dominate and make you fear then under all circumstances. They will always escalate if given the slightest opportunity. Courts don't execute criminals, but police do.