NEW LENOX, Ill. — A northeastern Illinois hospital has experienced a data breach that exposed patient information of up to 9,000 people.

Officials of Silver Cross Hospital in New Lenox said there’s no evidence showing any unauthorized people gained access to the data.

“Silver Cross Hospital recently learned that a vendor that manages parts of its website experienced a data incident that affected the information of certain Silver Cross patients and others,” hospital officials said on its website

The breach was discovered in June after the vendor upgraded its software in November.

Hospital spokeswoman Tracy Simons declined to name the vendor involved. She said she doesn’t know of any other hospitals affected.

The breach involves web forms submitted to the hospital between January 2013 and June 2017. The forms may have included people’s names, addresses, phone numbers, dates of birth, Social Security numbers, health insurance numbers and information about health conditions.

The hospital is planning to send letters to patients that could be affected and will offer identity protection to those patients who enroll by Nov. 11.

The hospital has also hired a forensics firm to investigate the breach.