I just got the game over Christmas. It took me forever to find those bombs too. I believe the bomb that you probably can't find is the same one that gave me trouble. Once you kill those first two guards, run into the closest building that is on the same level you are (I think it is D, but can't remember for sure). When you enter this building there are no enemies in it but is is one that you must clear, so it will come up showing you met an objective. Then stay to left and when it starts to get dark along that wall, look carefully and you will see some stairs. Go down them and follow that to the 3rd bomb. Let me know if you need more details and I will try to provide them.
Also, if you go to your objective screen by hitting select, you can play the movie and it shows a picture of what the bombs are attached too. These are helpful in recognizing when you are close to the bombs.
If anyone knows how to kill the chopper in the prison break level, let me know
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Oh, and here is some info I just found
SoCom