MARTINZ (CBS SF) — Contra Costa County officials began sending letters this week to potential victims of “unauthorized access to certain county employee email accounts” during a computer breach between July and August last year.

In a press release, officials said an investigation into the breech was completed on March 11 and letters and email alerts began being sent to potential victims on April 15.

READ MORE: Livermore Police investigate shooting death of teenage girl; 1st city homicide of 2022

The investigation determined that an unauthorized person accessed the accounts at various times between June 24, 2021 and August 12, 2021. But it did not determine whether any emails or attachments to the accounts were viewed. or uploaded by the unauthorized person.

“However, the county was unable to rule out this possibility,” officials said in the statement.

Upon review of what may have been viewed or downloaded, the investigation determined that these were emails and attachments containing information relating to certain county employees, as well as people who contacted the county Department of Employment and Human Services.

READ MORE: Shooting investigators find stabbed and bleeding victim in bullet-riddled vehicle in Sunol

“This information included names and one or more of the following: social security numbers; driver’s license or state-issued identification numbers; financial account numbers; passport numbers; and medical information and/or health insurance information,” officials said in the statement.

The county was offering free credit monitoring to eligible people. Authorities have also set up a dedicated, toll-free call center for people to call with questions about this incident and are offering free credit monitoring to eligible people.

Individuals with questions or those wishing to determine whether their personal information was contained in any of the email accounts may call 1-855-604-1854, Monday through Friday between 6:00 a.m. and 6:00 p.m. Pacific Time.

NO MORE NEWS: War in Ukraine sparks new US Army readiness drills in California desert

Additionally, the county’s website home page at www.contracosta.ca.gov contains information about steps individuals can take to help protect their personal information.