Hartford Public Schools in Connecticut postponed its first day of classes Tuesday following a ransomware attack that shut down the district's system.
Students were notified in an online message that in-person and online classes would not be taking place Tuesday.
"We have been informed by Metro Hartford Information Services (MHIS), our City of Hartford shared services team that manages our network infrastructure, that the ransomware virus caused an outage of critical systems and the restoration of those systems are not complete," the message read.
"This includes the system that communicates our transportation routes to our bus company and it is preventing our ability to operate schools on Tuesday."
Dr. Leslie Torres-Rodriguez, superintendent of Hartford Public Schools, told NBC Connecticut that they were able to restore the student-information system around midnight but are still working on the transportation system.
She said she does not believe the personal information of students and staff was compromised, but there will be an investigation.
The district, which has just over 18,000 students and nearly 1,600 teachers, hopes to hold classes on Wednesday.
"This is another example of how flexible we all have to be," Torres-Rodriguez told the outlet. "We were ready and we were excited, and we still are, to receive our students and staff. This was something that was out of our control and we're going to give it another try."
Last week, the Miami-Dade County Public School system in Florida was the target of multiple cyberattacks as it welcomed students back for the first week of school. According to the Miami Herald, the district was hit with 12 cyberattacks — some local and some from outside the United States — on Sept. 2.
"There was a malicious attempt; malicious, well-orchestrated, complex attempt at derailing, destroying the connection which is essential for our students and teachers," Miami-Dade Public Schools Superintendent Alberto Carvalho said last week.
A 16-year-old student at South Miami Senior High School was arrested on Sept. 3 in connection to the cyberattacks and charged with computer use in an attempt to defraud, a third-degree felony, and interference with an educational institution, a second-degree misdemeanor.
Police chief Edwin Lopez said he believes "that other attackers are out there."
"We will not rest until every one of them is caught and brought to justice," he said in a statement. "Cyber attacks are serious crimes, which have far-reaching negative impacts. Our message to anyone thinking of attempting a criminal act like this is to think twice. We will find you."