“Tens” of people died in an attack in China’s Xinjiang region early Friday morning, according to a report from Radio Free Asia.

The “serious violent attack,” which took place in Baicheng County in the region’s far west, left “at least 40” people dead, according to the US state-funded news site, including five police officers.

 location of Baicheng county
The location of Baicheng county (in red) within Xinjiang. Photo: Google Maps.

After the incident, large numbers of police were reported to have “sealed off” the area, with checkpoints set up at every intersection. The suspects were from the majority-Muslim and Turkic-speaking Uighur ethnic group that comprises most of Xinjiang’s population outside of capital Urumqi.

The incident, news of which has been blocked in the mainland, reportedly involved a knife attack at a coal mine followed by an attack on local police using explosives stolen from the mine.

File photo of armed police in Xinjiang
File photo of armed police in Xinjiang. Photo: People News.

Resource-rich Xinjiang has abundant oil reserves and is China’s largest natural gas-producing region. The exploitation of these resources by China’s state-run enterprises is a point of contention among separatists and other opponents of Beijing’s rule.

According to RFA, Baicheng is a hot spot for violent conflicts. In February this year, the county was the scene of an attack with explosives that killed four police officers and two government officials.

Veteran RFA reporters have estimated that only five percent of violent incidents in Xinjiang are acknowledged by China’s state-run news agencies.

Ryan Ho Kilpatrick is an award-winning journalist and scholar from Hong Kong who has reported on the city’s politics, protests, and policing for The Washington Post, Los Angeles Times, TIME, The Guardian, The Independent, and others