Health care company Ascension lost sensitive data for nearly 5.6 million individuals in a cyberattack that was attributed to a notorious ransomware gang, according to documents filed with the attorney general of Maine.

A May ransomware attack on Ascension, a U.S. healthcare giant with more than 140 hospitals and dozens of senior living facilities, allowed hackers to steal personal and sensitive health information on 5.

Ascension, one of the largest private U.S. healthcare systems, is notifying nearly 5.6 million patients and employees that their personal and health data was stolen in a May cyberattack linked to the Black Basta ransomware operation.

Healthcare provider Ascension has revealed the sensitive data of 5.6 million patients was compromised in a massive cyberattack earlier this year. The ransomware attack occurred in May and threw the company into turmoil,