Hong Kong (CNN) The live feed of the sixth Democratic presidential debate was cut without warning in China Thursday night during a discussion on allegations of human rights abuses in the country's western region of Xinjiang.

The screen went black just before 9 p.m. ET after PBS moderator Judy Woodruff asked Mayor Pete Buttigieg if the US should boycott the 2022 Beijing Olympics over China's alleged mass detention of its Uyghur citizens.

The feed from the PBS/Politico debate in Los Angeles remained cut for about nine minutes while candidates were asked about a range of China issues, including the Hong Kong protests and military tensions in the South China Sea.

Censors regularly screen live broadcasts on international media networks in China, ready to cut any segment from the air if it is deemed politically sensitive by the ruling Communist Party.

Viewers know that what they are seeing has been censored because the screen goes black and all sound cuts out.

CNN live feed of Democratic presidential debate goes to black in Beijing. Candidates were asked about China's human rights record & the mass detention of Muslim minorities in Xinjiang. #PresidentialDebate pic.twitter.com/DSQ9QRu5zA — Will Ripley (@willripleyCNN) December 20, 2019

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