Just a few weeks after The Hospital for Sick Children (SickKids) experienced a ransomware attack that took some of its systems completely offline, another major healthcare provider in Toronto has declared a "Code Grey" in response to a network outage.

The University Health Network, which includes Toronto General Hospital, Toronto Western Hospital and the Princess Margaret Cancer Centre, announced just before 1 p.m. on Monday that it was "currently experiencing" a digital outage.

"Thank you for your patience while we work to resolve the issue," reads a tweet published Monday afternoon.

"myUHN Patient Portal is down," wrote the Twitter account for UHN's patient portal similarly.

"There has been an unplanned downtime. Our digital team is investigating the issue. We hope to be restored soon. We apologize for the inconvenience. We will keep you all updated."

We're currently experiencing an outage with our network. Thank you for your patience while we work to resolve the issue.

— University Health Network (@UHN) January 9, 2023

The network's entire website, including its patient portal and pages for all of its individual treatment sites, is currently displaying a message that reads "http/1.1 Service Unavailable."

It is not yet clear what caused the outage, how long it will take to resolve, or if any patient records have been affected.

SickKids did note after its recent ransomeware attack that there had been no evidence of any personal information or personal health information being impacted.

University Health Network administrators have confirmed that the network remains in Code Grey as of Monday at 3 p.m. and that doctors can still access some records using a "down time system."

According to the Quinte Health Network, a Code Grey is activated at Ontario hospitals that experience "loss of utilities, such as power, telecommunications, sanitary sewage discharge, potable water, or closure of fresh air intakes, resulting in the potential loss of use of hospital facilities."