WASHINGTON (WJZ)— The Obama administration is assessing the impact of a massive security breach that could involve nearly every federal government agency and its workers.

Tonight, Homeland Security officials say the breach is the work of Chinese hackers!

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Derek Valcourt has the latest.

The breach of federal computer systems was first detected back in April–hackers believed to be based in China accessed computers in the Office of Personnel Management which handles federal employee records and the interior department.

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In all the breach exposed the personally identifiable information of 4-million current and former federal employees, including details about job assignments,  training and performance ratings–data that could be used to blackmail employees with classified information.

Valcourt: “We’re used to hearing about data breaches nowadays, why is this one significant?”

“We’re not talking about the average employee at Walmart or Home Depot we’re talking about people who secure our financial records, our government records, our laws, our security,” said Gary Buclous, Infoworks Technologies.

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Gary Buclous specializes in cyber security, he worries stolen information from federal workers with security clearances could be dangerous in the wrong hands.

“If somebody wants to sabotage us they get a federal employees ID, they get the social security, they can create an ID and do whatever they want to do,” Buclous said.

In a statement, the FBI said, “We take all potential threats to public and private sector systems seriously, and will continue to investigate and hold accountable those who pose a threat in cyberspace.”

A new government security system known as “Einstein” was used to confirm this latest hack, but it’s not clear why it didn’t detect the breach sooner.

The breach is still under investigation,  but at least one U.S. official said it’s possible this could affect almost every government agency.

Right now it’s not clear if information from employees of U.S. intelligence agencies was compromised.

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The Office of Personnel Management is in the process of notifying those affected by the breach, and is offering credit monitoring and identity theft insurance for 18 months.