A Massachusetts high school student went to in-person classes on the first day of school despite having tested positive for coronavirus days earlier, officials said.

Now, about 30 people who came in contact with the student at Attleboro High School are under a two-week quarantine.

The mayor of Attleboro, a city about 39 miles southwest of Boston, said the student was tested Sept. 9 and that the positive result came in Sept. 11. The student then went to school for the first day of classes on Sept. 14.

Mayor Paul Heroux said a public health nurse for the city spoke to the family on Tuesday and confirmed that the parents had known for days that their child had the virus before sending him to school.

"There's no question about whether or not the parent knew," Heroux said.

The high school's principal, Bill Runey, said administrators learned of the student's positive test result Tuesday.

“I knew that we were going to end up having some cases, but I didn’t expect they would be on the first day,” he said.