A health insurance marketplace that provides coverage for members of the US Congress and congressional staffers was found to be compromised on Wednesday, according to a letter apparently sent from House Chief Administrative Officer Catherine L. Szpindor to members of that chamber.Szpindor\u2019s office would not directly confirm or deny the authenticity of the letter, which was first published on Twitter by a reporter for the right-wing Daily Caller news site. However, a spokesperson for the CAO\u2019s office did confirm the data breach and pledged to communicate updates from law enforcement to affected legislators and staff.Another spokesperson, for DC Health Link, also confirmed that personal information for \u201csome DC Health Link customers\u201d was exposed on a public forum, and added that an investigation is underway.\u00a0\u201cConcurrently, we are taking action to ensure the security and privacy of our users\u2019 personal information,\u201d DC Health Link said in a statement. \u201cIn addition, and out of an abundance caution, we will also provide credit monitoring services for all of our customers.\u201dData breach affects thousands of government healthcare enrolleesAccording to the leaked letter, members of the House did not appear to be the specific targets of the attack, but it said that \u201cthousands\u201d of enrollees in DC Health Link were potentially affected.\u00a0The FBI, DC Health Link, and the US Capitol Police are all a part of the investigation, according to statements, and the latter agency said that there were few details available to the public at this stage.\u00a0\u201cOur agents are assisting the FBI with the ongoing investigation,\u201d a spokesperson from the Capitol Police\u2019s Public Information Office said via email. \u201cThere is more work to do before law enforcement can provide more details.\u201dThe House Administration Committee, headed by Representative Bryan Steil, a Wisconsin Republican, tweeted that it was \u201caware of the breach, and is working with the CAO to ensure the vendor takes necessary steps to protect the PII of any impacted member, staff, and their families.\u201dA joint letter, signed by both Speaker of the House Kevin McCarthy and minority leader Hakeem Jeffries and published on Twitter, asked the Executive Director of the DC Health Benefit Exchange Authority, Mila Kofman, to provide information on formal notification to affected members. It also asked for further detail on both the extent of the breach and on mitigation measures.CSO will post updates as more information becomes available.