Knife-wielding Uygur men killed three border security guards at a road checkpoint near the Xinjiang city of Kashgar yesterday morning, the third violent incident in the region in just over a week. The motive for the attack was unknown, a police official and state media said. The stabbings took place in Yamanya town, Shule county, which is about 30km south of Kashgar and administered by the city. The four or five attackers pulled up in a vehicle to a road checkpoint manned by four security guards before stabbing them. The victims, three killed and another injured, were all Uygur men in their 20s and 30s. The incident followed a bombing in Kashgar on August 4 which killed 16, and another series of bombings in Kuqa county roughly 400km to the east of Kashgar on Sunday, which resulted in 12 deaths, including those of 10 attackers. However, there was no evidence yet linking the stabbing to the Kashgar bombing, Xinhua said. The fourth guard, who was seriously injured, was taken to a local military hospital and is now in critical condition. The police official said no one had been arrested for the attack and authorities were still searching for suspects. The incident will likely add to tension in the area. Uygur men traditionally carry knives with decorative handles on their belts. 'The terrorist attacks will definitely have a negative effect on tourism development in Kuqa,' county chief Yusufujiang Memet was quoted by Xinhua as saying. Kuqa is along the old Silk Road.