Howard University canceled classes on Tuesday after its computer network was the target of a ransomware cyberattack, according to school officials. The historically Black university said it intentionally shut down its network after noticing “unusual activity” last week.

“The situation is still being investigated,” the university wrote in a statement. “Based on the investigation and the information we have to date, we know the University has experienced a ransomware cyberattack.”

Howard’s physical campus is only open to essential employees on Tuesday, the announcement said. Non-essential staffers have been directed to stay home. The school’s WiFi service will be down until further notice and only some applications are accessible, although it is not clear which ones. Howard said in an update Tuesday night that it is setting up an alternate WiFi network, but that would not be ready by Wednesday, prompting the university to cancel online and hybrid classes again. In-person classes will resume Wednesday, but the school warned that certain online classwork may not be accessible.

Students and staff were advised not to call the school’s helpline should certain university applications not work during this time. 

“This is a moment in time for our campus when IT security will be at its tightest,” the university said. “We recognize that there has to be a balance between access and security; but at this point in time, the University’s response will be from a position of heightened security.”

The school said there hasn’t been evidence of personal information being leaked, but that its investigation into the “highly dynamic situation” is ongoing. The university said it is working with the FBI and local government to protect personal data and that operational updates will be provided daily. 

“Remediation, after an incident of this kind, is a long haul — not an overnight solution,” Howard said.

Ransomware attacks on organizations across the world have increased by 93% in the first half of 2021, according to cyberthreat intelligence company Check Point Research. The company found education to be the sector with the most attempted cyberattacks in comparison to all other sectors, reporting an average of 853 attacks each week. 

Stephen Manley, the chief technology officer at Druva, a data protection software company, said schools and universities are “prime targets” for cyberattacks. 

“The attack on Howard University is yet another sign that cyberattacks are global, interconnected, and evolving,” Manley said in a statement. “Hackers, drawn by the lucrative potential of holding business-critical data hostage, are launching more sophisticated attacks every day.”

The FBI and Department of Homeland Security warned organizations to be on alert for ransomware attacks before Labor Day weekend as a series of high-profile cyber incidents have had a pattern of landing on past holidays.

Dan Patterson contributed to this report.