Four other agencies, along with a national intelligence panel, still judge that the pandemic was likely the result of a natural transmission, and two are undecided, reports say.

The gunman, identified as Anthony Dwayne McRae of Lansing, Michigan, shot himself to death after the rampage, reports say.

This follows searches of the homes of President Joe Biden and former president Donald Trump that also turned up classified documents.

Megan Hess operated a funeral home and a body parts entity from the same building in Montrose, Colorado.

The highly sensitive intelligence on Iran and China risked exposure of US spying methods, the Washington Post says.

It says some White House staffers conducted official business on personal electronic messaging accounts that were not copied or forwarded to their official accounts, in violation of the Presidential Records Act.

Trump has said in social media posts that he declassified the records, but his lawyers have skirted the issue in court.

The Justice Department is investigating Trump for retaining government records – some marked as highly classified, including 'top secret' – at his Mar-a-Lago estate in Palm Beach after leaving office in January 2021.

Trump is under investigation for retaining government records, some of which were marked as highly classified, at the resort in Palm Beach, Florida, his home after leaving office in January 2021.

The FBI recovered more than 11,000 government documents and photographs during its Aug 8 search at Trump's Mar-a-Lago estate, according to court records.

Of the more than 11,000 government records and photos, 18 were labelled as 'top secret', 54 were labelled 'secret' and 31 were labelled 'confidential'.

Trump's legal team has argued that the former president wants to protect materials that could be subject to a legal doctrine known as executive privilege, which can shield some presidential communications.