De profundis

I'm really eager about a song which a heard on this documental movie about 9/11. You can hear it at 35:30 for example. I think that the beautiful female voices sing "De Profundis" but I'm not sure. Can somebody identify this song, I would be really grateful!

http://video.google.de/videoplay?doc...akv2EDA&q=11+9

Nobody can help me?