Chinese state media say two girls have died after eating poisoned yoghurt placed outside their kindergarten at the direction of the head of a rival school. According to the Associated Press, Xinhua News Agency says police believe the poisoning was motivated by competition for students between the schools. The agency claims that the woman confessed that she injected the yoghurt with rat poison and asked a man to place it with notebooks on the road to the rival kindergarten in Pingshan county in Hebei province. Xinhua said Thursday that the girls\' grandmother found the books and yoghurt and took them home on April 24. The children suffered convulsions after drinking the yoghurt and died later. Xinhua said police detained the woman and the man. Police referred queries to Pingshan county\'s information office. Calls there rang unanswered.