CNN  — 

Several members of the graduating class at The Lovett School in Atlanta, Georgia, have tested positive for Covid-19, according to a letter from the school.

“The school has been notified by several Class of 2020 families that their students have tested positive for COVID-19,” the letter from Head of School Meredyth Cole and Head Nurse Shana Horan said.

It is unclear how many students have tested positive.

Families of the infected students “are working with the appropriate healthcare professionals and Departments of Health,” according to the letter.

The Lovett School, which is in the northwestern part of the city, closed its campus in mid-March. The school is an independent, coeducational day school that serves students kindergarten through 12th grade, according to the website.

Traditional graduation ceremonies were postponed until later in the summer but a drive-through graduation parade was held May 17, according to CNN affiliate WSB.

Lovett High School in Atlanta, Georgia

According to an email sent to parents from Cole and Horan on Friday, “the school was notified a graduating senior who had attended the drive-through festivities on May 17 had tested positive for COVID-19,” the Atlanta Journal Constitution reported.

The student who attended drive-through graduation and later tested positive “was confined to his or her car while on campus.” That student “later had company over for a graduation gathering, and then traveled out of town with friends,” Cole and Horan wrote in an email obtained by the AJC.

At this time, it is unknown how the student contracted the virus. It is also unclear if the virus was spread to other graduates at the drive-in event or during the off-campus gathering, the AJC reported.

CNN has reached out to the school administration for additional information.