A ransomware attack at Baltimore County Public Schools has the district closed to students again.
CNN  — 

Baltimore County Public Schools will reopen Wednesday after a ransomware attack forced the system to close for three days.

The district shared the update Monday night on social media accounts, saying that schools would return to virtual learning.

In order for class to resume, the school system listed four things that would have to happen. Most include faculty and staff conducting a confidence check on their computers and other technology to make sure that their equipment was not compromised.

Students and staff can perform computer checks to determine whether they need a new device.

The district said on its Facebook page over the weekend that there would be no classes Monday and Tuesday.

“Our focus today and for Monday and Tuesday is identifying and addressing student and staff device needs so that instruction can continue,” the post said. “We now know that BCPS-issued Chromebooks were not impacted by the cyberattack.”

The cyberattack last Wednesday closed the 25th largest school district in the country. The district has 115,000 students.

The district at that time confirmed the attack on its Twitter account, writing:

“BCPS can now confirm we were the victim of a Ransomware attack that caused systemic interruption to network information systems. Our BCPS technology team is working to address the situation and we will continue to provide updates as available.”

Ransomware is a type of malware, or malicious software, that encrypts a victim’s files. The attacker then typically demands a ransom from the victim to restore access to the data upon payment. School officials have been tight-lipped on specifics of the investigation into the attack.

The school district has been providing updates via social media since the discovery of the attack.

“We understand how challenging this situation is for families and staff, and we thank you for your patience as we work through this crisis,” BCPS said.

CNN’s Ganesh Setty and Oliver Janney contributed to this report.