Tennessee’s testing company is investigating a “deliberate attack” on its data center, state education officials said, interrupting student tests for the second day in a row.

“It appears Questar’s data center may have experienced a deliberate attack this morning based on the way traffic is presenting itself,” Education Commissioner Candice McQueen said in an email to school directors Tuesday morning. “The attacker may take these same steps again, and Questar is actively working on further reinforcements, including notifying authorities.”

Officials with Questar, the state’s testing company, said they became aware of a problem at about 8:45 a.m. CST when students could not log on or submit their tests.

“At this time, we are investigating the cause. Initial findings indicate it is external to our online delivery platform,” said Brad Baumgartner, chief operating officer of the Minnesota-based company. “We are working with our hosting vendor to determine the root cause and have taken necessary measures to allow students to resume successful testing. At this time, testing has resumed.”

But many districts already had suspended tests for the day, including ones in Bartlett, Collierville, Germantown, and Knoxville.

“Our plan is to begin testing again tomorrow, once we receive information from the state that issue has been resolved,” said Carly Harrington, a spokeswoman for Knox County Schools.

Shelby County Schools left the decision up to its high school principals.

“We’ve told our schools that if you’re able to keep going to keep going,” said Superintendent Dorsey Hopson.

Unlike the problems experienced Monday, many high school students across the state were able to log in to the TNReady test beginning at 8 a.m., but problems began to emerge within the hour.

“Things were going OK, and then our students started having problems,” said James Evans, a spokesman for Rutherford County Schools. “Either they couldn’t log in, or they were not able to upload information when they were done, or the test just stopped and knocked them out of the system.”

State and Questar officials did not immediately respond to questions about who might have attacked the system, but the state said Questar would notify authorities and “is actively working on further reinforcement” in case the attacker strikes again.

The disruption to students, classes, and school schedules was sweeping.

“Any time you have parents preparing, teachers preparing, students preparing and you get ready for game day and you start the game and then the game is called off, and then you have to start and stop, all of those things have an impact on your kids’ ability to do their best,” Hopson told Chalkbeat.

The second day of interruptions also created a logistical nightmare for teachers, said Leigh Ann Skaggs, a high school teacher in Chester County.

“Teachers have had to create lesson plans last minute, figure out how to continue to stretch out plans to prepare students for a test we aren’t sure they’re going to take, and hype them up for a test that may not happen at this point,” she said. “We are in a holding pattern to see what happens next. I’m not holding my breath.”

One Bartlett parent echoed a sentiment many educators have felt as Tennessee’s transition to a new test and online system have been fraught with problems.

“This is a very high-stakes test that impacts student report cards, teacher evaluations, and employment, and even determines soon-to-be letter grades for schools and districts,” said Jennifer Proseus. “Why do these faulty tests — that parents and teachers are forbidden from seeing — hold so much power?”