U.S. intelligence agencies were working Monday night to verify the strong possibility that al-Qaida's No. 2 figure, the leader of its virulent Yemen offshoot, has been killed, intelligence officials said.

The officials spoke on condition of anonymity because they were not authorized to be quoted discussing a classified action. The Washington Post reported that Nasir al-Wuhayshi was targeted in a CIA drone strike last week.

Arab media, and extremists on Twitter, reported that al-Wuhayshi, a top lieutenant to al-Qaida leader Ayman Al Zawahri, was killed in the strike. U.S. officials told The Associated Press they are investigating evidence to that effect, while declining to confirm the CIA's role.

The SITE Intelligence Group, which tracks social media postings by Islamist groups, translated a series of messages by AQAP sympathizers that Wuhayshi had died.

Wuhayshi leads al-Qaida in the Arabian Peninsula, or AQAP, which is considered the terror group most capable of striking American interests.

Arab media reports said three suspected al-Qaida members were killed June 9 in an apparent U.S. drone strike in Mukalla, a southeastern port city in Yemen.

"If confirmed, the death of AQAP's leader is a major blow to Islamist terrorists who are plotting daily to attack America," said Rep. Michael McCaul, a Republican who chairs the homeland security committee.

Rep. Adam Schiff, the ranking Democrat on the intelligence committee, said Wuhatshi's death "would be a significant blow to the core of the terrorist organization and its most dangerous franchise."

As al-Qaida 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-Qaida factions aligned with Zawahri in the face of rival pressures" from the Islamic State group.

Wuhayshi's death would be a 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.