WASHINGTON • Top lawmakers in Congress were briefed Tuesday on the investigations into classified documents found in the private possession of President Joe Biden, former President Donald Trump and former Vice President Mike Pence.

U.S. Director of National Intelligence Avril Haines was among the officials who met privately with congressional leaders for roughly an hour. Attending the briefing were the House and Senate leaders of both parties and the leaders of both intelligence committees, who comprise what’s known as the “Gang of Eight.” Lawmakers leaving the briefing declined to specify what was discussed.

Both Republicans and Democrats have long demanded more information from the Biden administration about the successive discoveries of classified documents in the homes of two presidents and a vice president. The U.S. strictly controls who has access to classified material and how they can view it.

Leaders of the intelligence committees have expressed concerns about the possible exposure of highly classified secrets in those documents.

“We still have considerable work to do, oversight work to do, to satisfy ourselves that absolutely everything is being done to protect sources and methods,” Rep. Jim Himes, D-Conn., the top Democrat on the House Intelligence Committee, said in an interview.

The chairman and vice chairman of the Senate Intelligence Committee issued a joint statement that also called for more information about any potential damage.

“While today’s meeting helped shed some light on these issues, it left much to be desired and we will continue to press for full answers to our questions in accordance with our constitutional oversight obligations,” said Sens. Mark Warner, D-Va., and Marco Rubio, R-Fla.

Federal agents searched Trump’s Mar-a-Lago residence in August after developing evidence that led them to believe that Trump and his representatives had not returned all classified files.

Biden’s lawyers have said they discovered a “small number” of classified documents in November after searching a locked closet at the Penn Biden Center for Diplomacy and Global Engagement. A second batch of documents — again described by Biden’s lawyers as a “small number” — were found in a storage space in Biden’s garage near Wilmington, Delaware, along with six pages located in Biden’s personal library in his home.

FBI agents in January found six additional items that contained documents with classified markings and also took possession of some of Biden’s handwritten notes, according to Biden’s lawyers.

Pence’s lawyers have also said they found a “small number of documents” in his Indiana home that appeared to have been inadvertently taken there at the conclusion of his vice presidency. Federal agents found an additional classified document during a voluntary search.