Foshan is a city in central Guangdong, which has had an outbreak of new cases since late May.
In the provincial capital of Guangzhou, mass testing of residents has been carried out in several districts while lockdowns have been imposed in certain neighbourhoods.
Authorities also imposed more restrictions on business and social activity in Guangzhou in efforts to curb the coronavirus spread.
China also reported 27 new asymptomatic infections, versus 25 a day earlier. China does not classify symptomless infections as confirmed cases.
As of Friday, China had a total of 91,394 confirmed infections. Its death toll stood unchanged at 4,636.