LAS VEGAS (KLAS) — University Medical Center is notifying patients of a data breach that occurred in mid-June, and offering free identity protection services for those who were affected.

The data breach was “by a well-known group of cybercriminals that seek to use the information for commercial gain,” according to UMC.

Letters received this week in the Las Vegas valley indicate that the breach occurred in June 14 and was shut down the following day, according to UMC officials.

UMC says it notified the FBI and Metro police of the breach.

8NewsNow first reported the breach on June 30, but the hospital denied the breach occurred at that time.

“We have no evidence to date that UMC’s clinical systems, including those interfaced with our electronic health record, were accessed,” the letter says. “However, we have determined that certain files on our network servers were compromised.”

Among the information exposed during the cyberattack: names, addresses, dates of birth and social security numbers. UMC also says “certain protected health information” was compromised, although, “We have no direct evidence of the misuse of your specific information.”