Yonkers-based Empress EMS was a victim of a cyberattack, according to a letter sent to patients earlier this month.

Empress says an unauthorized party first gained access to certain systems on May 26.

The letter says that party copied a small subset of files on July 13, with the breach being discovered the next day.

Many of the impacted files were used by Empress for billing purposes and contained documents with the patient's name, Social Security number, dates of service and the name of their insurer.

Empress is offering impacted patients a free 12-month membership in Experian Identity Works.

A hacking site says ransomware gang Hive was the perpetrator.

It's not known if Empress paid any ransom.

While initially confirming the breach, Empress told News 12 it had no further comment.