The Obama administration is scrambling to assess the impact of a massive data breach that may have impacted nearly every federal agency, according to The Associated Press.

The breach has been apparently linked to Chinese hackers who have gained access to the personal data of 4 million current and former federal employees, reports from multiple outlets, including the Washington Post, stated.

The Office of Personnel Management (OPM), which is the human resources department for the federal government and issues security clearances, says the breach took place in December, but was detected in April.

OPM says data breach was detected in April. DHS says it's known about breach for a month. OPM warns employees today. — Steven Portnoy (@stevenportnoy) June 4, 2015

A congressional aide familiar with the situation, who declined to be named because he was not authorized to discuss it, says the OPM and the Interior Department were hacked. A second U.S. official who also declined to be identified said the data breach could potentially affect every federal agency. Initially, officials said the breach only involved the OPM.

One key question is whether intelligence agency employee information was stolen. Former government employees are involved in the breach, as well.

The White House was considering a public announcement of the breach Thursday night or Friday morning, the second official said.

FBI statement on government #cyber incident and information from OPM: http://t.co/XR0j2bAwoS — FBI (@FBI) June 4, 2015

In November, a former Department of Homeland Security official disclosed another cyberbreach that compromised the private files of more than 25,000 DHS workers and thousands of other federal employees.

The OPM conducts more than 90 percent of federal background investigations, according to its website.

UPDATED 5:45 p.m. PT to include FBI statement.

Additional reporting by Mashable.