Computer systems at the University of Calgary were partially operational on Monday following a virus attack that knocked its network offline over the weekend, according to Global News.

Students and staff received the following warning on Saturday: "Do not use any UCalgary-issued computers for any purpose."

A malware attack was believed responsible for disabling IT services, including email, Skype VPN, secure wireless and Active Directory.

One professor, commenting on video, believed because most systems affected were Microsoft-based, the malicious software targeted Windows systems or an exploitable flaw in Windows.

It will be a few days before systems are fully operational, the university stated, and an investigation has been launched to determine who hacked in and why.

By yesterday, the university's AirUC secure wireless and Office 365 email were functioning and officials informed students and staff that it was again safe to use university-issued computers to access networks and applications.