More than 900 students and staff members have been instructed to self-isolate after a school district in Georgia reopened last week.

Dozens of tests came back positive, leading one high school to be temporarily shut down, according to a statement from Cherokee County School District superintendent Dr. Brian V. Hightower. There have now been 59 confirmed cases following the reopening, with the surge prompting the district to require a two-week quarantine for 925 students and staff members that might have been exposed to COVID-19.

The high school that’s been shuttered is Etowah High School, which hopes to resume in-person learning on Aug. 31. The school has 14 confirmed cases with an additional 15 tests pending. A group picture of Etowah’s senior class went viral at the beginning of the month, where the students were photographed without face coverings.

“As a result of the confirmed cases, 294 students and staff are under quarantine and, should the pending tests prove positive, that total would increase dramatically,” Hightower wrote. The district is conducting contact tracing for each positive case and notifying parents. Quarantined students will have to take virtual classes and the school will be deep-cleaned before reopening again.

Cherokee County schools welcomed students back on Aug. 3. Wearing a face mask wasn’t mandatory for students, though Hightower pushed for it.

“As we said before reopening, social distancing is not possible in all situations at our schools—this is why we require our staff to wear masks or face shields when they cannot distance, and this is why we're providing masks to students and strongly recommending they wear them,” he said in an announcement Friday. “This is a critical component is to keeping schools open.”

Georgia schools are facing criticism after a photo of a crowded school hallway went viral on Twitter, showing that students weren’t practicing social distancing and many weren’t wearing masks. A few days later, nine confirmed coronavirus cases were reported at North Paulding High School and it was subsequently shut down. The student who shared the photo was also suspended.