A Fulton High School student is suspected of hacking into the district's computer network, shutting down the system for several hours.
The 17-year-old student was arrested on suspicion of tampering with computer equipment in last week's incident.
Fulton Police Chief Steve Myers says he's unsure what motivated the hacking. He says the school's information technology department traced the security breach to a classroom computer and reported to police the teenager was behind the hacking.
Myers says he can't release further details because of an ongoing investigation.
A district spokeswoman says no personal information or sensitive school data were stolen in the attack.