A data breach at Houston-based CenterPoint Energy affected more than 1 million Texans, according to a filing with the Texas attorney general's office, ABC13 and KPRC reported.

The state's data breach database lists 1,062,060 Texans as affected, KPRC reported. The information involved includes customers' names, addresses, Social Security numbers and driver's license numbers, according to the filing.

The report was posted on the attorney general's website on Monday, KPRC said. It showed that affected people had not yet been notified when the information was submitted, and the state notes that the number of people affected may be updated later, according to KPRC.

CenterPoint first disclosed the incident in a Sept. 14 filing with the U.S. Securities and Exchange Commission, KPRC reported. At the time, the company said it had learned of an online post by a third party claiming to have obtained customer information, but it did not say how many customers were affected, ABC13 and KPRC reported.

"CenterPoint Energy continues to actively investigate the cybersecurity incident disclosed last month," the company said in a statement, the stations reported. It said it brought in outside cybersecurity, forensic and legal advisers and is working to determine which customers will be notified under the law.

"CenterPoint's delivery of electric and gas services has not been impacted and remains operational and undisrupted," the company said.

The security news site SecurityWeek reported that a hacker had claimed in September to hold nearly 7.5 million records and posted an archive that seemed to contain about 3 million phone numbers. CenterPoint also serves customers in Indiana, Minnesota and Ohio, SecurityWeek said, and the Texas filing covers only people in Texas.

What we know: More than 1 million Texans' personal data, including Social Security numbers, was exposed.
What we don't: Who was behind the breach and when customers will be notified.