Police in Lod, southeast of Tel Aviv, are at a loss to explain how Arab terrorists were able to place a bomb on train tracks in the city\'s Ganei Aviv neighborhood. The bomb exploded early this morning, lightly injuring three people and damaging one train car. Police, who believe that it was detonated by remote control, arrested several Arabs found to be in the area illegally. Security personnel who combed the tracks each morning did not spot the bomb today before it went off. Train service on the route was stopped for an hour, and has since resumed.