A coordinated cyberattack has compromised the personal health information of approximately 11 million patients across three interconnected hospital networks in the southeastern United States. The breach, discovered last week, involved ransomware that encrypted critical systems and exfiltrated patient data including medical histories, Social Security numbers, and insurance information.

The affected hospital networks, which share a common electronic health records platform, have engaged federal law enforcement and leading cybersecurity firms to investigate the breach and restore systems. Emergency departments remained operational through backup procedures, but elective surgeries and outpatient appointments were disrupted for several days.

The Department of Health and Human Services has opened an investigation into the breach, which ranks among the largest healthcare data compromises in U.S. history. Cybersecurity experts say the attack highlights the vulnerability of interconnected healthcare systems and the urgent need for the sector to invest in security infrastructure, staff training, and incident response planning.