(Bloomberg) — The U.S. Health and Human Services Department suffered a cyberattack Sunday night during the nation’s response to the coronavirus pandemic, according to three people familiar with the matter.

The attack appears to have been intended to slow the agency’s systems down, but didn’t do so in any meaningful way, said the people, who asked for anonymity to discuss an incident that was not public.

The National Security Council’s tweet on Sunday night was related to the hacking and the release of disinformation, according to the people. The government realized Sunday that there had been a cyber intrusion and false information was circulating.

NSC tweeted just before midnight: “Text message rumors of a national #quarantine are FAKE. There is no national lockdown. @CDCgov has and will continue to post the latest guidance on #COVID19.”

The tweet was in part meant to address the hacking, which involved multiple incidents. Secretary of State Michael Pompeo and other Trump administration officials are aware of the incident, the person said.

It doesn’t appear that the hackers took any data from the systems, one of the people said. HHS officials assume that it was a hostile foreign actor, but there is no definitive proof at this time.

HHS did not immediately respond to request for comment. White House and National Security Council did not immediately respond to requests for comment.

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