U.S. Health and Human Services suffered a cyber-attack on its computer system Sunday night, three sources told Bloomberg.

Officials believed the attack was from a hostile foreign actor, and was designed to slow the agency’s services amid the government’s rollout of a response to coronavirus, but failed to register a meaningful impact and did not appear to remove any data, the sources said.

The hack allegedly tried to overload HHS servers with millions of hits in just hours. A source told Bloomberg that Paul Nakasone, who heads the National Security Agency and U.S. Cyber Command, is looking further into the matter to determine who was behind the attack.

The National Security Council reportedly attempted to address the hack and the release of disinformation by tweeting 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 NSC said.

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. #coronavirus

— NSC (@WHNSC) March 16, 2020

U.S. officials are grappling with widespread school and business closings to stem the spread of the virus as the world’s death rate surpassed that of China’s, where coronavirus originated.

New York City mayor Bill de Blasio said Sunday that all bars and restaurants in the city, save takeout services, would close, along with the city’s public-school district — the largest in the nation.

“To say the least, this is a very troubling moment, a moment where I am just distraught at having to take this action,” de Blasio said at a Sunday press conference. “But I became convinced over the course of today that there was no other choice.”