Tesla Motors (TSLA) is under a federal investigation into its car search engines, which were breached by hackers that stole data on more than 700,000 users and accessed customer information.
The FBI is looking into whether Tesla knew about the hack or whether it should have done more to prevent it.
Tesla released a statement late Monday saying it is “reviewing the matter,” but did not provide further details.
The company’s Chief Executive Officer Elon Musk said the company is working to make the breach “unavoidable.”
The company said it was working with the Federal Trade Commission (FTC) to investigate the hack.
Musk said Tesla “has not taken any actions to address this issue,” and the company’s “systems have been audited” and “a thorough audit has been conducted to confirm all systems were secure.”
He said that, as of Monday, the company had identified the hackers responsible for the breach, and that the company was “currently reviewing our internal procedures and policies to prevent a recurrence.”
Tesla’s car search platform, known as Autopilot, was not affected.
Musk described the incident as a “misstep,” but added that “we are reviewing the steps we took to prevent this from happening again.”
Tesla, like many car manufacturers, has been under fire from privacy groups and lawmakers for failing to adequately disclose that it stores user data.
The FTC said that the data stolen includes credit card information, phone numbers and email addresses.
Musk told reporters on Monday that Tesla is “actively investigating” the hack, but declined to comment further.
The Federal Trade Office said it is investigating the breach.
The FTC said it will send a letter to Tesla demanding the company hand over customer information, which is a violation of its terms of service.
The agency also asked Tesla to provide “all information required by the FTC” about how it processes consumer complaints, which Musk has not provided.
Musk has said that Tesla should have implemented a system of self-report by users, and said Tesla should be required to disclose data about its customers’ online activities, including whether they were the subject of a breach.
Tesla’s stock, which has gained 18 percent since the breach was disclosed, is up nearly 14 percent since last week.
The incident comes as the automotive industry has been rocked by a spate of security breaches.
Tesla said it found more than 20 hacks last year and that hackers stole more than 50 million consumer and commercial data.
In January, Tesla recalled nearly 1.5 million vehicles because of data breach.
Tesla also said it discovered an unauthorized access to personal information, including credit card numbers, at one of its suppliers.
Last month, Tesla CEO Elon Musk announced that he would resign from the company, citing personal reasons.