BEIJING, China (CNN) -- At least 16 police officers were killed, and 16 more were wounded, after an attack on a border police station in western China on Monday morning, the state-run Xinhua news agency reported.
The attackers crashed a heavy truck into the station and detonated two grenades, according to Xinhua. The incident happened in Kashi, in the Xinjiang Uygher Autonomous Region.
The violence comes just four days before the start of the Summer Olympic Games in Beijing.
Last month, police said they had cracked five terrorist groups in the autonomous region where attackers hit the police station on Monday. Authorities said the groups were allegedly plotting to sabotage the Olympics, Xinhua reported.
The Xinjiang Uygher Autonomous Region is home to a Sunni Muslim ethnic minority.
Uygurs in Xinjiang are supposed to enjoy regional autonomy, as guaranteed by China's constitution, but some seek independence.
Millions of Han Chinese, the country's dominant ethnic group, have migrated into Xinjiang over the past 60 years, prompting complaints that they dominate local politics, culture and commerce at the Uyghers' expense.
The dissatisfaction has turned violent at times, including several and sometimes deadly bus bombings in 1992 in the provincial capital, Urumqi.
Officials blamed such incidents on Uygher groups who seek an independent Muslim state.
China insists only a small minority of Uygher support the separatists.