Telecommunications giant Comcast says a data breach involving a vendor used to collect debts from customers impacted nearly 238,000 current and former Xfinity subscribers whose personal information may have been compromised.

The data breach was disclosed in a regulatory filing made with the attorney general’s office in Maine this month, through which Comcast officials said it had identified 237,703 customers who were likely affected by the incident.

The breach involved a company called Financial Business and Consumer Solutions (FBCS), which Comcast utilized to collect overdue payments from its Xfinity TV and Internet subscribers.

Comcast said it was initially contacted by FBCS in March with an advisory about the data breach, but was told that customer data was not impacted. The financial firm issued a supplemental advisory in July that was based on new information, which concluded that Comcast subscriber data was involved in the incident.

The breach took the form of a ransomware attack, through which hackers compromise computer systems used by a company and encrypt files that they promise to unlock if a payment is made. It isn’t clear if FBCS paid a ransom to the hackers who compromised their systems; federal law enforcement officials generally advise against making those types of payments to hackers.

Comcast says FBCS followed up on their March notification four month later, with new information that indicated hackers had downloaded records that included the personal information of some of its customers. Comcast’s own systems were not affected, the company said in a disclosure notice sent to customers.

Comcast said personal information that may have been obtained by hackers included account credentials for Xfinity services, as well as names, addresses, Social Security numbers and dates of birth. The company offered complementary identity theft protection services to affected customers.