U.S. Sens. Brian Schatz and Mazie Hirono are among 13 Senators calling for an investigation into National Security Agency surveillance programs recently uncovered by media that may place at risk the privacy of millions of Americans.

In a letter sent today to the Privacy and Civil Liberties Oversight Board — an independent agency created by Congress charged with overseeing actions of the executive branch — the senators detailed their concerns over the two programs, one that gathers hundreds of millions of U.S. cellphone records; the other collected Internet usage data on foreign users from nine U.S. tech companies. 

The letter asks the Board to make it an urgent priority to determine whether the programs are “conducted within the statutory authority granted by Congress” and “take the necessary precautions to protect the privacy and civil liberties of American citizens under the Constitution.” 

The programs are authorized under provisions of the Foreign Intelligence Surveillance Act.

All senators are scheduled to be briefed on the programs Thursday by officials from the NSA, the Department of Justice, the Federal Bureau of Investigation and it’s Office of the Director of National Intelligence.

Members of the Senate Intelligence Committee were briefed Tuesday. All House members also were invited to a similar briefing.

Schatz in December voted against a measure reauthorizing amendments made in 2008 to the Foreign Intelligence Surveillance Act, his first vote as a newly-appointed senator. As a member of the House in 2012, Hirono did not cast a vote on the reauthorization bill. She had voted against the amendments in 2008.