LANZHOU -- Northwest China's Gansu province reported four new locally transmitted confirmed COVID-19 cases between 11 pm Tuesday and 11 am Wednesday.

The four people, three from the provincial capital Lanzhou and one from the city of Zhangye, are all close contacts of a previously confirmed case, according to a statement from the provincial health commission.

The province has registered a total of eight locally transmitted confirmed COVID-19 cases and two asymptomatic cases since new local infections were reported Tuesday.

On Wednesday, local authorities temporarily closed three popular grottoes including a UNESCO World Heritage site, the Mogao Grottoes, to visitors in efforts to contain the spread of infections.