When you drop down, the doors open and a big, armored Solarii with a metal shield emerges. Select the SMG and hold the Aim button (Right Mouse Button, L1 on PS3, L2 on PS4, LT on Xbox), keeping him targeted as he approaches.

When he lunges toward Lara, continue to hold Aim and press Dodge/Roll (Shift/Circle/B) as you move to the left or right to evade his attack.

NOTE: You may also be able to perform a dodge without moving to either side. Continue to hold Aim and when the big guy attacks, just press Dodge/Roll. I found moving to either side worked best, but try both and see what you think.

When you dodge this way, the enemy turns aside momentarily, exposing his body...

...so you can shoot him.

Repeat the process: Hold Aim and target his shield. The white reticle means you can't do any damage. So be patient.

When he gets close, continue to hold Aim and press Dodge/Roll plus left, right or back. Here Lara goes right.

The big guy is caught off balance and momentarily turns to expose his vulnerable side and back.

Now your bullets do damage—a lot of damage if you're using the machine gun.

When the big man falls, the doors burst open again and another demolitions guy starts lobbing Molotov cocktails at you. Take him down quickly to avoid getting burned. The 2 guys who opened the door for the big man seem to have run off rather than face Lara. Can you really blame them?

Loot the bodies, especially the big guy, who carries a BOW PART. This is one of two parts you'll need to upgrade the Makeshift Longbow into the more effective Recurve Bow. You'll get the other part a bit later in the game.

NOTE: If you forget to loot the big guy's body and leave the area or reload so that his body disappears, don't fret. You can return here later from any fast travel camp and you'll find the BOW PART in one of the salvage crates on the middle floor of this building.