Continue through the masoluem to the forest. Engage the enemies here. You can climb or have your partner climb the ledge to the left to have a good firing position. After clearing the area, a vehicle will bring in reinforcements from the rear. Destroy it and kill the opposition then another vehicle will bring in more troops from the path ahead.
Before moving to the last area, dig in and take out the snipers to the left. Kill the remaining enemies in the area. Be careful of the brute that will appear when you're near the doorway. Continue inside to complete the section.