More than 200 children have caught coronavirus after attending the same summer camp.
Up to 260 kids and staff were infected at the getaway retreat in Georgia, US, at the end of June.
The camp, which the Center for Disease Control and Prevention (CDC) did not name, has been criticised for not requiring kids to wear face masks.
Many buildings also did not have proper ventilation.
The CDC revealed that more than 200 of those infected were children, meaning more than a third of those who attended caught the infection.
Georgia Governor Brian Kemp issued an executive order on June 11 allowing campers and workers to attend overnight camps if they received a negative COVID-19 test within 12 days of starting camp.
The camp ran from June 21 to 27, and more than 500 of the campers and staffers were children aged under 17, the CDC reported.
On June 24, a teenage staff member who had been experiencing chills while at the camp tested positive for the virus.
While campers began to be sent home that same day, the camp did not officially close until three days later, the CDC said.
People sleeping in the same cabins and "engaging in regular singing and cheering" also "likely contributed to transmission," the CDC said.
Children between the ages of six and 10 had the highest infection rate — the number of positive cases divided by the total number of attendees — at 51%, followed by those aged 11-17 at 44%.
The CDC said that what happened at the camp indicates that "children of all ages are susceptible" to coronavirus, especially when placed in large group settings, and "might play an important role in transmission."
Georgia has been the US' fifth worst-hit state for coronavirus with more than 190,000 cases.
There were 73 more deaths recorded in the state on Saturday.
