In Chapter 8, right before you choose to kill (or don't kill) one of the two guys hanging. Konrad mentions that he tired to leave the city with 1,500 people but they all died. Now as you know it's later revealed that Konrad is a voice inside of Walker's head (Or vice versa :S).
So, logically... Walker, tried to leave the city with 1,500 people but they all died... Or maybe it's nothing IDK.
Not changing sig till we get a sequel to Freedom Fighters. Started 13/4/2010
"Evacuation of Dubai ended in complete failure, death toll, too many." That is the last sentence on Konrad's distress call which breaks through in a lull during the storm. They were last in communication with Dubai as Konrad was preparing to leave the city with the survivors so Walker would probably know from older reports how many were a part of the caravan and his subconscious estimated the mortality rate based on "too many."
I guess the best way to describe Rez is if a DJ game and Star Fox had a baby, and that baby was on acid...