Al Qaeda in the Arabian Peninsula (AQAP) said early Tuesday that its leader and the terror organization's second-in-command, Nasir al-Wuhayshi, had been killed in a U.S. drone strike in Yemen.

A video statement released by the terror group's media wing confirmed al-Wuhayshi's death, and said that his deputy, Qassim al-Rimi, had been named as AQAP's new leader.

"Our Muslim nation, a hero of your heroes and a master of your masters left to God, steadfast," senior operative Khaled Batrafi said in the video, vowing that the group's war on America would continue.

"In the name of God, the blood of these pioneers make us more determined to sacrifice," he said. "Let the enemies know that the battle is not with an individual ... the battle led by crusaders and their agents is colliding with a billion-member nation."

There was no immediate statement from U.S. officials, who had been working to confirm al-Wuhayshi's death even as social media accounts affiliated with extremist groups were reporting it. A counter-terrorism source who tracks social media accounts tied to Al Qaeda and ISIS told Fox News late Monday that a credible account based in Yemen was reporting that al-Wuhayshi had been killed in the CIA strike and al-Rimi was AQAP's new leader.

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There was also no comment from the CIA, who referred questions about the drone strike to the National Security Council.

The death of al-Wuhayshi, a former personal secretary to Usama bin Laden, is the latest in a series of targeted killings of AQAP's top leaders, including its most senior military leader Nasr al-Ansi, religious ideologue Ibrahim al-Rubish and others in recent weeks.

Al-Wuhayshi was among 23 Al Qaeda militants who broke out of a detention facility in Yemen's capital, Sanaa, in February 2006. In 2009, al-Wuhayshi announced the creation of AQAP, which gathered together Yemeni and Saudi militants.

AQAP is the terror group considered most capable of striking U.S interests. It recently claimed responsibility for the January attack on the offices of the French satirical magazine Charlie Hebdo.

Intelligence sources told Fox News that al-Wuhayshi was in or around the port city of Mukalla in Yemen when the strike took place this past Friday. Arab media outlets reported that three suspected Al Qaeda members were killed June 9 in an apparent U.S. drone strike in Mukalla. It is not clear if this was the same strike that targeted al-Wuhayshi.

"If confirmed, the death of AQAP's leader is a major blow to Islamist terrorists who are plotting daily to attack America," Rep. Michael McCaul, R-Texas, the chairman of the House Homeland Security Committee, said earlier Monday.

Rep. Adam Schiff, D-Calif, a ranking member of the intelligence committee, said al-Wuhayshi's death "would be a significant blow to the core of the terrorist organization and its most dangerous franchise."

As Al Qaeda leaders have been captured or killed, Schiff said, "Zawahri has been increasingly reliant on a small cadre of loyal lieutenants. As one of those top lieutenants, al-Wuhayshi has played an important role in keeping Al Qaeda factions aligned with Zawahri in the face of rival pressures" from ISIS.

Al-Wuhayshi's death is a major setback for AQAP, but the group's master bombmaker, Ibrahim Hassan al-Asiri, is believed to still be alive. He is thought to have designed bombs that were slipped past security and placed on three separate American-bound airplanes, although none of them exploded.

The group has also been able to expand its reach in recent months as Yemen has slid into chaos. Shiite rebels known as Houthis captured Sanaa last year and are battling southern separatists, Islamic militants and local and tribal militias across the country. Yemen's military, once a close U.S. ally against Al Qaeda, has split between opponents and supporters of the rebels, and a Saudi-led coalition has been bombing the Houthis and their allies since March.

Earlier this year, AQAP took advantage of the chaos to seize Mukalla.

Al-Rimi, the new leader of AQAP, is thought to be the brains behind a series of attacks, including a foiled plot to mail bombs to the United States and multiple attacks against Yemen's U.S.-backed government. In writings and videos, he has vowed to topple the Sanaa government and strike America.

In a May 2011 eulogy for bin Laden, al-Wuhayshi had warned Americans "the matter will not be over" with the death of Al Qaeda's founder and that "what is coming is greater and worse."

Fox News' Catherine Herridge and the Associated Press contributed to this report.