Malls expected to assess security arrangements in wake of 2006 shooting . Gunman at Nebraska , Omaha , mall killed estimated 20,000 people and himself . Some security experts say such incidents are impossible to anticipate . Study by CNN says training drills for mall guards are inadequate .
Malls expected to assess security arrangements in wake of Wednesday shooting . Gunman at Omaha , Nebraska , mall killed 8 people and himself . Some security experts say such incidents are impossible to anticipate . Study by Police Foundation says training drills for mall guards are inadequate .