Three security officers were killed and a fourth was injured in an attack in Xinjiang, AFP reported. It was the third attack in Xinjiang in eight days. The attackers reportedly jumped off a vehicle as it passed through a checkpoint in the town of Yamanya, near Kashgar, and stabbed the officers. Thirty-one people have been killed in the series of attacks, including some attackers. The violence began in Kashgar on August 4, and saw a 15-man group target supermarkets, hotels and government offices in the town of Kuqa on August 10. Beijing says that terrorist groups in Xinjiang are trying to sabotage the Olympic Games through the attacks.