Alabama Power, Georgia Power and their parent company, Southern Company, have confirmed that an unauthorized third party gained access to information associated with approximately 400,000 customer accounts through the company’s online customer portal.

According to notification emails being sent to affected customers, the unauthorized access involved limited contact and account information, including customers’ names, addresses, phone numbers, email addresses, the last four digits of Social Security numbers and other basic account details.

The company said the compromised information did not include bank account numbers, payment card numbers or driver’s license numbers.

“Southern Company recently detected suspicious activity involving our online customer portal,” the company said in a statement. “An unauthorized third party accessed certain, limited information about the accounts of approximately 400K customers.”

Southern Company said it took immediate steps to stop the unauthorized activity after it was detected and notified law enforcement.

The company said it has since conducted an investigation and has not identified evidence of ongoing unauthorized access.

“We understand the trust our customers place in us and remain committed to protecting their information,” Southern Company said.

The company is currently notifying customers whose information was affected and said those customers will be provided with free credit monitoring.

Customers who receive a notification from Alabama Power, Georgia Power, or Southern Company are encouraged to carefully review the information provided and take advantage of the credit-monitoring services being offered.