The Chinese government and exiled Uighur groups are offering differing explanations about what led to the latest instance of unrest in the troubled Xinjiang region, where scores of people were killed this week.
The official Xinhua news agency said the violence began when a mob armed with knives and axes attacked a police station, government offices, and civilians in two towns Monday in Shache county, killing dozens of civilians.
Xinhua said police responded with gunfire, killing dozens of members of the mob.
It said an initial investigation indicates the incident was a "premeditated terrorist attack," language commonly used by Beijing to describe unrest in Xinjiang.
The government's account was disputed by exiled Uighur groups.
In a statement, the Uyghur American Association condemned what it called the "use of excessive state violence." It said the residents were protesting against Beijing's "heavy-handed Ramadan crackdown" and "extra-judicial use of lethal force in recent weeks."
Quoting local sources, the association said more than 20 Uighurs were killed and at least 70 arrested during the incident.
China severely limits foreign media reporting in the region, making it difficult to independently confirm those numbers.
Although the attack took place early Monday, it took nearly a day for even official media to report on the region's latest violence, which has become a very sensitive topic in China.
Around 200 people have died in unrest over the past year in Xinjiang, home to Muslim minority Uighurs.
The violence has led Beijing to launch a year-long crackdown on what it calls terrorism in the region. Hundreds have been detained in the crackdown so far.
Many Uighurs said they are the victims of state-sanctioned discrimination and repression, including restrictions on Muslim religious practices and favoritism toward the Han majority.
Beijing denies that it discriminates against the Uighurs.
Rights groups said the crackdown on Uighurs is particularly harsh during the Muslim holy month of Ramadan, saying many Muslims are prevented from fasting.