Baltimore County Public Schools shut down Monday and Tuesday following a ransomware attack that paralyzed the school system’s network last week right before Thanksgiving.

According to the Baltimore Sun, officials described the event as a “catastrophic attack on our technology system.” The ransomware attack is reported to have hit the entire Baltimore County Public Schools’ network on Wednesday. The attack caused the 115,000 students who were solely remote learning to have an extended Thanksgiving weekend as schools were shut Monday and Tuesday and will resume on Wednesday.

When resuming school tomorrow, the District is advising students and staff that they can use Chromebooks, but not Windows-based devices while the investigation is ongoing. Students and staff are performing a series of security checks on system-issued devices and any students who need a new device or assistance can get assistance at their local public high school.

According to social media accounts, some teachers have surmised that the ransomware strain involved in the attack is Ryuk, which is well- known to have been involved in previous attacks against municipalities and school systems.

At the present time, the attack is being investigated and it is unknown whether or not any personal student or employee information was compromised.