I have found the last two.

The first plaza, after clearing out the seven, saving the boy, clearing out another five, head past the blue barricade. Clear out the enemies beyond, move a little further ahead, then backtrack all the way back to the first plaza. Another 2 DG Snipers appear. One is by the white billboard on the south end, while the other is in the Northwest building of the western alleyway.

I'd like to take credit for this but really, the guide is what pointed them out.