Freight shipping giant Estes Express Lines has started informing more than 21,000 individuals that their personal information was stolen in a recent ransomware attack.

The incident was identified on October 1, 2023, and the investigation into the matter determined that the attackers gained access to the company’s network on September 26, 2023.

While residing in the network, the attackers accessed and extracted data from some of Estes’ systems, and deployed ransomware.

Estes says that a forensic investigation into the incident was concluded on November 7, but notification letters started being sent to the affected individuals only in December, after law enforcement concluded their own investigation into the incident.

The personal information that was compromised in the attack, Estes told the Maine Attorney General’s Office, included names, other personal identifiers, and Social Security numbers.

“Estes is not aware of any identity theft, fraud, or financial losses resulting from this incident,” the company said in the notification letter to the impacted individuals, a copy of which was submitted to the Maine AGO. The company told the Maine AGO that just over 21,000 individuals were affected.