Rescuers combed through mangled wreckage early Sunday searching for survivors after two passenger trains collided in southern Poland , leaving at least 16 dead . NEW : A U.S. citizen is among the dead , consulate confirms . NEW : Finding more survivors is unlikely , duty officer says . Comment: The rescue operation is complicated , a firefighter says .
NEW : A U.S. citizen is among the dead , consulate confirms . NEW : Finding more survivors is unlikely , duty officer says . Comment: The rescue operation is complicated , a firefighter says .