The number may very well be low, but on the other it could high also. The majority of the folks crossing the border are from Mexico and even though we have apprehended over 500 people from Middle Eastern countries, it is impossible to guess the nationality of the ones that get through.
It is possible that these were the only ones, but it is unlikely.
Also, remember that the problems with the INS are with management and the past and current immigration policy, not the troops in the field.