NEW : Two Americans of Arab descent are believed to be involved in 9/11 plot . NEW : Authorities are piecing together clues gleaned from flight logs and manifests . NEW : A third plotter is believed to be have traveling in Europe . Comment: Meanwhile , heightened security was visible Saturday in New York and Washington as intelligence officials worked to pin down information about the potential threat . Andrew Cuomo directs state police to help with security at major transport hubs .
NEW : Two Americans of Arab descent are believed to be involved in 9/11 plot . NEW : Authorities are piecing together clues gleaned from flight logs and manifests . NEW : A third plotter is believed to be have traveling in Europe . Comment: Andrew Cuomo directs state police to help with security at major transport hubs .