U.S.-based Radio Free Asia reports that ethnic Uyghurs attacked police with knives and bombs at a traffic checkpoint in China's far western Xinjiang region, and at least 18 people were killed.
The attack occurred at the beginning of the Muslim fasting month of Ramadan on June 22 in the southern city of Kashgar, where tensions between Muslim Uyghurs and the majority Han Chinese have led to bloodshed in recent years.
Hundreds have been killed in violence across the region, blamed by Beijing on Islamist militants.
Citing local police sources, Radio Free Asia said that suspects killed several police officers with knives and bombs at a traffic checkpoint in Kashgar, then armed police killed 15 suspects "designated as terrorists."
It said in all between 18 and 28 people were killed, including several bystanders, but that police estimates of the toll varied.
Chinese Foreign Ministry spokesman Lu Kang told reporters that he could not immediately verify the report.
China has around 20 million Muslims, only a portion of whom are Uyghur.