Joe Biden addressed the matter of classified documents that were recovered from his private office at the Penn Biden Center for the first time on Tuesday, saying that he was surprised to learn they were there and is cooperating fully with the Justice Department’s review.

“Let me get rid of the easy one first,” Biden began in response to a slew of reporter questions at the North American Leaders Summit in Mexico City. “People know I take classified documents and classified information seriously.”

Biden said his personal attorneys found the classified documents as they were clearing the office.

“They did what they should have done. They immediately called the [National Archives] … turned them over to the Archives, and I was briefed about this discovery and surprised to learn that there were any government records that were taken there to that office,” the president added. “But I don’t know what’s in the documents. My lawyers have not suggested I ask what documents they were.”

The documents, which were from Biden’s time as vice president, were discovered on Nov. 2 at the Penn Biden Center, according to Richard Sauber, special counsel to the White House. The president used the think tank as a private office from mid-2017 until the start of the 2020 campaign.

“The documents were not the subject of any previous request or inquiry by the archives,” Sauber said on Monday in a statement.

“Since that discovery, the President’s personal attorneys have cooperated with the Archives and the Department of Justice in the process to ensure that any Obama-Biden Administration records are appropriately in the possession of the Archives.”

Attorney General Merrick Garland tapped U.S. Attorney for the Northern District of Illinois John Lausch, a Trump appointee, to review the matter.

Biden said Tuesday that he hopes that investigation will be finished soon.