Initial reports suggest the outbreak could be due to a student's father, who tested positive last week.
Authorities in Fujian have ordered that all teachers and students must be tested within a week, after more than 100 cases were reported in four days.
The first cases there have been linked to a primary school.
The suspected source of the outbreak is a student's father who tested positive for the virus on 10 September - 38 days after returning from Singapore on 4 August.
It is not clear if the student's father was indeed infected overseas, as such a long incubation period is very unusual.
The cases come ahead of a week-long National Day holiday on 1 October, known as Golden Week that sees millions travel across the country.
Chinese youth are discovering surfing in increasing numbers, thanks in part to restrictions on foreign travel in the wake of the pandemic.
World now sees twice as many days over 50C.
World now sees twice as many days over 50C
World now sees twice as many days over 50C6
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