LANZHOU -- Lanzhou, capital of Northwest China's Gansu province, suspended in-person classes for local kindergartens, primary and high schools, and off-campus training institutions starting Thursday for COVID-19 control.

Vocational middle schools and colleges in the city have been put under closed-off management, the Lanzhou municipal education department said in a circular released Wednesday night.

The move aims to beef up anti-epidemic measures to protect the lives and health of local residents, the circular stated, adding that resumption of classes is subject to further notice.

Health authorities had collected 11,326 samples for nucleic acid testing from nine schools in Lanzhou, with all samples testing negative, said the information office of the provincial government.

Gansu reported five locally transmitted confirmed COVID-19 cases on Wednesday, including four in Lanzhou, according to the National Health Commission.