The University Health Network (UHN) says most of its digital systems are back up and running following a widespread outage Monday, which triggered a Code Grey.

“So we remain in a Code Grey until we are fully confident that all the information is back in the system, but we are providing care today,” UHN Spokesperson Gillian Howard told CP24. “There will be delays because it does take a little while to get back up into the information in the system but people should come to the hospital and expect that their care will continue.”

In a statement to CP24 Tuesday morning, the hospital also said that it is “confident” that the outage was not caused by a cyber attack, and that patient data was not compromised.

“We are confident that this was not a cyber attack and work throughout the night has restored virtually all systems and ensured that they are stable,” UHN said. “There was no breach of patient data as the problems with the systems were entirely internal.”

The outage Monday affected digital systems at Toronto General Hospital, Toronto Western Hospital, Princess Margaret Cancer Centre and the Toronto Rehabilitation Institute. The UHN patient portal and website were also down. It began around noon and made it more difficult for clinicians to access patient data.

“I want to confirm that it is not a cyber attack,” Howard reiterated. “And we are very thankful that this was an internal matter and now we have to look at our systems and make absolutely sure that we know what happened.”

She said the problem generally related to connectivity between systems in the hospital.

While the hospital network said it is confident that systems will be fully restored today, it nevertheless advised patients coming to UHN hospitals that there may be some delays.

“The work needed to input all of the information about the care delivered yesterday into the system will take place throughout the day. There will be delays to scheduled care today, as there were yesterday and we regret the inconvenience and worry that this has caused for patients and their families,” UHN said.

It added that “there will also be work to ensure that we correct the causes of the failure.”

The integrity of digital systems at hospitals has been top of mind recently. Last month a ransomware attack forced a Code Grey at the Hospital for Sick Children (SickKids). It took several weeks for the hospital to restore most of its systems.

A “Code Grey” is usually implemented when there is a loss of essential infrastructure at a hospital.