Jason Gonzales | The Tennessean

The nationwide ACT exam experienced a security breach, causing the cancellation of tests in Tennessee and in some districts nationwide.

Tennessee is most impacted by the breach because it is the only state to offer a statewide retake program, said Ed Colby, ACT spokesman.

The first of three opportunities for Tennessee high school seniors to retake the test was scheduled for Tuesday, with that exam date canceled. Colby said the compromise in the testing process is under investigation.

"We aren’t releasing any details at this time," Colby said. "There was a compromise in the testing process and how we refer to it is anything that can impact the fairness of the exam."

Tennessee Education Commissioner Candice McQueen notified districts on Thursday of the cancellation and forwarded an email Friday morning from ACT's Chief Operating Officer Janet Godwin to districts that said the nonprofit canceled the test date "to ensure the exam is fair and valid."

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Godwin's email says districts will be able to use Oct. 16 as the initial test date, with Oct. 30 as another option.

It's unclear how many Tennessee districts are affected by the cancellation, Colby said.

"We deeply regret that you are affected by this unfortunate situation and sincerely apologize for any inconvenience it may cause you, your staff, and students," Godwin's email says.

Breaking: TNDOE to reschedule the October 2 ACT after an out of state security breach is reported. This is good news for you students. You will have a little more time to prep. Let's get ready!!!!! pic.twitter.com/H9EIPaCvlb — Dr. Mike Looney (@wcsDirofSchools) September 28, 2018

Any tests administered prior to Oct. 16 will not be scored, according to Godwin's email

"For districts that cannot participate in either day, ACT will make vouchers available to enable students to test on December 8 at an available Saturday test center," Godwin's email says.

McQueen, in the forwarded email, asked districts to reach out to ACT for any further guidance on the test date's cancellation or the administration of the test.