OAKLAND (KCBS) – Alameda County library patrons have received a disturbing email from county officials, saying the library’s records had been hacked.

READ MORE: Fatal Crash, Fire Involving Big-Rig Prompts Closure Of Eastbound Richmond-San Rafael Bridge

An email to library members says officials were contacted last month by someone claiming to have information from the library system’s entire database of users. That contact included the names and addresses of about three dozen library patrons.

READ MORE: UPDATE: Lockdown Of Hercules Neighborhood Lockdown Due To Police Activity Lifted

The person also threatened to sell the information.

Officials say the contact did not claim to have other information the library collects, like birth-dates and drivers’ licenses.

MORE NEWS: Homeless Encampment On BART Property In Concord Evicted

The library does not collect sensitive information such as Social Security numbers or credit and debit card numbers.