Aides to President Biden have discovered a second trove of classified documents in a different location from the last set, a person familiar told NBC News.

The classification level, number and exact location of the documents is still unclear.

On Monday it was reported that attorneys for the president had in November discovered documents at his office in the Penn Biden Center in Washington, D.C., which he used after his time as vice president.

Since the White House said Monday that Biden’s attorneys had found 10 documents with classified markings at an old office at a Washington, D.C. think tank, the president has been peppered with questions about the discovery.

Biden was asked about the documents at the top of his trilateral press conference Tuesday in Mexico City, alongside Mexican President Andrés Manuel López Obrador and Canadian Prime Minister Justin Trudeau.

The president said he was ‘surprised’ to find out classified documents were discovered in a box in a locked cabinet. But said his lawyers ‘did what they should have done.’

‘They immediately called the Archives – immediately called the Archives, turned them over to the Archives,’ the president said.

The documents were discovered on November 2 and handed over to the Archives on November 3.

Biden said he didn’t know the content of the documents and that his lawyers suggested he not ask.

‘And we’re cooperating fully with the review,’ the president added.