NEW YORK, May 9 (Xinhua) -- Canvas, an online learning platform used by thousands of schools and universities worldwide, partially restored services Friday after a major outage linked to a cyberattack.

Earlier on Thursday, several U.S. universities, including the University of Michigan and Harvard University, had alerted students that the platform was unavailable.

Instructure, the parent company of Canvas, later confirmed the incident after hours of shutdown. "Instructure discovered the unauthorized actor involved in our ongoing security incident made changes to the pages that appeared when some students and teachers were logged in," the company said in a statement Friday. "Out of an abundance of caution, we immediately took Canvas offline to contain access and further investigate."

The hacking group ShinyHunters claimed responsibility for the breach at Canvas and alleged it had accessed data from more than 275 million users across nearly 9,000 schools.

Instructure disclosed last week that it had experienced a "cybersecurity incident perpetrated by a criminal threat actor," adding that it had enlisted forensic experts to minimize the impact of the breach.

The compromised data included personal information such as names, email addresses, student ID numbers and Canvas messages, said Steve Proud, Instructure's chief information security officer. ■