LANZHOU -- Northwest China's Gansu province had suspended in-person classes for 1,915 schools as of Thursday for COVID-19 control, a provincial education official said Friday.

The suspension of classes has affected over 780,000 students as well as nearly 80,000 teachers and staff members in the cities of Lanzhou, Jiayuguan, Zhangye and Jiuquan, said Wang Guangya, deputy head of the provincial education department.

Local education authorities will be offering online classes before in-person classes are resumed, Wang added.

As of Thursday, the province had a total of 18 locally transmitted confirmed COVID-19 cases and one asymptomatic carrier, said Zhang Hao, deputy director of the provincial health commission, adding that all of them are in stable condition.

Local health authorities have collected more than 4 million samples in mass nucleic acid testing to screen COVID-19 infections, Zhang said.