“Sometimes when I look around me and see so many Han, I feel like I am a stranger in my own homeland,” said a Uighur engineer in Aksu, the prefectural capital, which was once predominantly Uighur but whose population is now half Han.

Local officials, mindful of how social unrest can hobble careers, may be worried about angering higher-ups in Beijing. But one Communist Party official interviewed by Radio Free Asia provided another reason for the media blackout: “We are controlling information about the incident so strictly, lest we frighten Han migrants in Aksu,” he said.

A man who answered the telephone at the Baicheng government’s offices hung up when asked about what had happened at the mine. Ma Yanfeng, an official charged with managing foreign visitors to Aksu, said he knew nothing about the attack, but expressed no evident concern when told the grisly details. “I think you’ll find that the different ethnic groups in Aksu live together in absolute harmony,” he said, spreading his arms wide for effect.

Although much of the violence in Xinjiang goes unreported by the Chinese news media, the authorities often find it hard to conceal clashes with large death tolls, or those that provoke serious civil unrest. Those include a clash in the nearby city of Kashgar in June that left as many as 28 people dead, and a protest near Aksu last year that followed the fatal shooting of a Uighur teenager, who was reportedly gunned down after he failed to stop at a police checkpoint.

The government invariably blames Muslim religious extremists for the violence, though analysts outside China say many attacks have little to do with jihadist ideology. “The triggers are often locally embedded, whether it be reprisal for a woman who’s been publicly unveiled, and her family shamed, or people striking back after a relative has been detained by police,” said James Leibold, a professor of Asian studies at La Trobe University in Melbourne, Australia, who is an expert on Xinjiang.

Radio Free Asia, citing a government official in Baicheng, said the attackers might have been seeking vengeance for what the official described as a coercive campaign aimed at combating religious extremism. The official said the 17 suspects being sought were members of three Uighur families who had been singled out for flouting regulations that, among other prohibitions, bar women from veiling their faces.