Canada-based Carleton University on Tuesday stated that it has detected an attempt by an external group or individual to hack into its IT network.

The university said that any system accessible from the main network, that is Windows based, may have been compromised. It recommended users to refrain from using Microsoft Windows systems and to shut down their computers.

“Individuals may see ransom-ware messages appear on their screens, demanding payments via bit coins.  Users are asked to ignore all messages seeking a payment and are encouraged to report these messages to the CCS Help Desk”, it added.

In the latest update on the matter, the university said that it is open and classes are continuing. Also, it said that users on campus are encouraged to use their computer to conduct business if they are able to do so.

A university student told CBC News that the hackers have demanded payment in bitcoin. According to the message displayed on the school computer, the attackers are asking for either two bitcoin per machine or 39 bitcoin (nearly $30,000 at press time) in total to release the encrypted files. The total number of infected systems remains unknown at the time of writing.

"We're trying to sort out the details still," said Steven Reid, a media relations officer at Carleton, as quoted by CBC News. "It's affecting multiple systems, but we don't know the extent."

Earlier in June, the University of Calgary was under a similar attack, in which it university paid a ransom of $20,000 to regain access to its systems. More recently, the San Francisco Municipal Transportation Agency (SFMTA) has been hacked and the attackers have reportedly demanded 100 bitcoins as ransom.