A system that thousands of schools and universities use was offline Thursday due to a cyberattack, creating chaos as students tried to study for finals and underscoring education's dependence on technology.

The hacking group named ShinyHunters claimed responsibility for the breach at Instructure, the company behind the learning management system Canvas, said Luke Connolly, a threat analyst at the cybersecurity firm Emisoft.

CBS News has reached out to Instructure for comment.

Some of the universities which have reported being targeted include Penn State, the University of Wisconsin-Madison, Columbia University and Union College New Jersey.

UCLA was among several California schools that reported being crippled by the outage.

Also impacted in the Chicago area were Northwestern University, the University of Chicago, the University of Illinois Chicago and the University of Illinois.

In a message to students, Penn State said that "no one has access" to Canvas, and a "resolution" was not expected "within the next 24 hours."

The school said all tests scheduled for Thursday and Friday in its Pollock Testing Center were canceled.

The student newspaper at Harvard reported that the system was down there, too. And public school districts also sought to reassure parents, with officials in Spokane, Washington, writing that they aren't "aware of any sensitive data contained in this breach."

Canvas is used to manage grades, course notes, assignments, lecture videos and more. The hacking group posted online that nearly 9,000 schools worldwide were affected, with billions of private messages and other records accessed, Connolly said.

Screen shots he provided showed that the group began threatening Sunday to leak the trove of data, giving deadlines of Thursday and May 12. Connolly said the later date indicates that discussions regarding extortion payments may be ongoing.

Rich in digitized data, the nation's schools are prime targets for far-flung criminal hackers, who are assiduously locating and scooping up sensitive files that not long ago were committed to paper in locked cabinets. Past attacks have hit Minneapolis Public Schools and the Los Angeles Unified School District.

Instructure has not posted about the attack on its social media.

Connolly said the Canvas attack is strikingly similar to a breach at PowerSchool, which also offers learning management tools. In that case a Massachusetts college student was charged.

Connolly described ShinyHunters as a loose affiliation of teenagers and young adults based in the U.S. and the United Kingdom. The group also has been tied to other attacks, including one aimed at Live Nation's Ticketmaster subsidiary.