Staff at Winnipeg's Health Sciences Centre continued to work from paper records on Thursday as cybersecurity teams scrambled to contain a ransomware attack that disabled key clinical systems, the Manitoba Nurses Union said. The disruption forced delays to some scheduled procedures and diagnostic services.

The attack affected access to electronic health records, laboratory results and imaging systems at the province's largest hospital. Shared Health, the agency overseeing Manitoba's healthcare network, engaged cybersecurity specialists and law enforcement to investigate the breach and restore operations.

The Manitoba Nurses Union warned that manual workarounds increased the risk of medication errors and slowed patient care, particularly in emergency and intensive care units. Union president Darlene Jackson said frontline staff needed clearer guidance and additional support while systems remained down.

Hospital administrators said patient care remained the priority and emergency services stayed open. They urged the public to seek care as normal while declining to confirm whether a ransom demand had been made or whether patient data had been compromised, citing the ongoing investigation.

The incident renewed scrutiny of cybersecurity defences across Canadian healthcare systems, which have faced a rising number of attacks in recent years. Manitoba's privacy officials said they had been notified and would review whether personal health information was exposed.