HARTFORD, Conn. (WTNH) — Connecticut Attorney General William Tong’s office is investigating following a data breach involving Webster Bank, according to officials.

Tong’s office confirmed that it is working with the bank and Guardian Analytics, the vender involved, in the investigation.

The bank notified Tong’s office about the breach on April 10. It began mailing noticed to impacted Connecticut residents the same day.

Tong’s office said that 153,754 banking customers in Connecticut were impacted. Of those, 117,278 had their name and account numbers exposed, and 36,476 had their names, account numbers and social security numbers exposed.

The bank told the office that it doesn’t believe customers are at risk, and is providing two years of credit monitoring for those who are impacted. State law requires companies to offer the credit monitoring if there has been a data breach.