U.S. intelligence and counterterrorism officials are testifying before Congress about the deadly September attack on the U.S. consulate in Benghazi, Libya.

The Senate Intelligence Committee is holding a closed hearing on the attack, which resulted in the deaths of U.S. Ambassador Christopher Stevens and three other Americans. A House panel is hearing testimony from foreign policy experts.

Many lawmakers have raised concerns about whether there was adequate security at the consulate, and if the Obama administration later attempted to conceal information to avoid any embarrassment before the November 7th presidential election.

Former CIA Director David Petraeus is scheduled to appear in a closed session Friday before the House Intelligence Committee. Petraeus resigned last week, following an FBI investigation that uncovered his extramarital affair with biographer, Paula Broadwell. The incident also raised concerns about a possible breach of national security.

In another development, House Foreign Affairs Committee chairwoman Ileana Ros-Lehtinen said Secretary of State Hillary Clinton will testify before a committee next month.

During his press conference Wednesday, President Barack Obama spoke out against what he termed “outrageous” criticism by Republican lawmakers against the U.S. ambassador to the United Nations, Susan Rice.

Following the attack, Rice made several public comments that it grew out of a spontaneous protest over an anti-Muslim film produced in the United States. Information later surfaced the attack was planned by al-Qaida.