Upper Darby High School reportedly will be closed Friday in response to an online threat of violence.

Upper Darby police declined late Wednesday night to comment, but the department's Twitter account retweeted Philip Heron, editor of the Delaware County Daily Times, reporting that Upper Darby police had arrested someone after the threat was made and that Friday classes at the high school were canceled.

CBS3 reporter Joe Holden tweeted that the school was ordered closed due to an undisclosed threat, but police "don't believe there's any substance" to the threats.

Parents reportedly had received an email message from Dan Nerelli, superintendent of the Upper Darby School District, announcing the closure. While police "can't substantiate that a threat is imminent" of a "potential shooting," Nerelli said he canceled classes and sports activities scheduled for Friday "in an abundance of caution."