Eighteen People, 16 Saudis and two Sudanese, have been killed in flash floods as a result of torrential rains in different parts of Saudi Arabia over the past week, the Saudi daily (Arab News) reported Wednesday. Saudi Civil Defense Chief Lt. Gen. Saad Al-Tuwaijri urged Saudis and expatriates to keep away from valleys at times of flooding, warning that \"crossing flooded valleys in vehicles is a dangerous act,\" and that no force can stop floods having strength of 20 tons. He added that helicopters would not be able to carry out rescue operations at times of heavy rains and powerful winds.