AIKEN, S.C. (AP) — At least two children in South Carolina have died of COVID-19 this month as schools have reported thousands of cases among students and staff.

The Aiken County coroner confirmed a 9-year-old and a 15-year-old died from the virus on Sept. 1. Aiken County Public Schools had previously announced the deaths of two students in fourth and tenth grade.

The state’s current coronavirus surge has continued to infect more children and younger people, and affect them more severely, than earlier in the pandemic.

Health officials tracked more than 20,000 cases between Thursday and Sunday of Labor Day weekend.