GENEVA - Victims of a suspected chemical attack in Syria on Tuesday appeared to show symptoms consistent with reaction to a nerve agent, the World Health Organization said on Wednesday. 'Some cases appear to show additional signs consistent with exposure to organophosphorus chemicals, a category of chemicals that includes nerve agents,' WHO said in a statement, putting the death toll at at least 70. 'The likelihood of exposure to a chemical attack is amplified by an apparent lack of external injuries reported in cases showing a rapid onset of similar symptoms, including acute respiratory distress as the main cause of death,' it said.