A hacker stole personal information on about 40,000 employees of the U.S. Department of Homeland Security (DHS) and posted it online, TechCrunch reported on Oct. 28 local time.

The leaked information included names, titles, email addresses, mobile phone numbers and office locations, the report said.

Information on border and immigration enforcement officers, cybersecurity staff and senior officials was also exposed.

The hacker, using the name "Department of Peace", claimed to have extracted the data from the Okta single sign-on (SSO) system used by DHS employees and contractors to log into a central network.

The hacker also left a note saying, "They have our information, so it is fair for us to have theirs." The leaked data was also passed to the nonprofit group DDoSecrets, TechCrunch reported.

More than half of the leaked records, about 21,000 entries, involved U.S. Customs and Border Protection (CBP) employees. The data also included information on 10,000 employees of U.S. Immigration and Customs Enforcement (ICE) and its Homeland Security Investigations (HSI) unit, and about 1,000 employees of the Cybersecurity and Infrastructure Security Agency (CISA).

The leak amounts to about one-fifth of DHS's total workforce of 220,000. Time information in the records indicates the data was taken around mid-August.

The data also contained information on surveillance technology that employees can access.

The data included dozens of employee groups using services from surveillance company PenLink. PenLink has claimed its technology can track the locations of hundreds of millions of mobile phones.

The incident is the second leak DHS has suffered this year. DHS did not immediately respond to a TechCrunch inquiry, and Okta said there was no evidence its data or systems had been compromised.