A 16-year-old boy has been arrested in Northern Ireland after a cyberattack disrupted access to educational systems used by potentially hundreds of thousands of students.

The boy, who has not been named for legal reasons, was arrested Wednesday in Portadown, County Armagh, on suspicion of offenses under the Computer Misuse Act.

The Police Service of Northern Ireland (PSNI) said he has been released while detectives from its cybercrime team continue their investigation, which has included an additional search following the arrest.

It comes as the “C2K” system shared by almost all schools in Northern Ireland was taken offline earlier this month following an unspecified attack.

The Education Authority (EA), which oversees school support services, said Wednesday the incident was “a targeted attack on a small number of schools which is believed to have compromised some personal data.”

The EA said it would be notifying individuals and schools impacted by the attack, depending on guidance provided by the PSNI and the Information Commissioner’s Office.

“It remains the assessment of our system managers that the cyber incident is contained. Additional security measures were deployed at the beginning of this month on detection of the incident,” the EA said.

“Intensive work continues to ensure schools are fully reconnected to the C2k system and that all impacted systems return to normal.”

The vast majority of schools in the region are connected to C2K, which provides online services including access to teaching materials, assignments, exam revision and communication tools.

There are around 300,000 pupils and 20,000 teachers in Northern Ireland, according to official statistics, although there has been no formal confirmation of how many individuals might have been impacted by the incident..

The EA said previously it was making “good progress” restoring access and was prioritizing pupils “at critical points in the academic year,” particularly those due to sit examinations.

In some cases, schools opened during the Easter holiday period to help students reset passwords and regain access. Officials said work will continue over the coming days to fully restore services, adding that the need to secure the system must be balanced against pressure to bring it back online quickly. 

The EA has apologized for the disruption and said it will continue to provide updates as the situation develops.