Nine Uighurs "armed with knives, swords and sickles," stormed the station's guard post in Bachu county's Serikbuya township near the city of Kashgar on Saturday, police station chief Liu Cheng told Radio Free Asia.
The men killed two unarmed auxiliary policemen before attempting to advance on the main office, Liu told the US-funded service.
Two police officers were also injured in the attack at about 5:30 pm (0930 GMT,) the official Xinhua news agency reported.
Twenty-one people died in clashes between Uighurs and security forces in the same county in April.
The incident comes at a time of increased tension in Xinjiang after five people died when a car ploughed into a crowd in Beijing beside the portrait of Mao Zedong at the gate of the Forbidden City near Tiananmen Square on October 28.
 Beijing has blamed Uighur separatists backed by the militant East Turkestan Islamic Movement.
Some eight million Uighurs make up about 40 per cent of the 21.8 million people in the vast, ethnically divided region of Xinjiang.
The Uighurs complain of cultural and religious repression and claim that ethnic Han Chinese migrants enjoy the main benefits of development in the oil-rich but economically backward region.
The government has accused some Uighurs of links to terrorist groups in neighbouring Pakistan, Afghanistan and Central Asia.
Read more: http://voiceofrussia.com/news/2013_11_17/11-killed-in-assault-on-police-station-in-Xinjiang-0529/