The Central Command said the U.S. forces killed the militants using "a combination of small arms fire and precision airstrikes" to attack the compound, believed to be used as a "safe haven" by senior al-Qaida leaders.
The Defense Department said the operation was conducted with the support of Yemen's government. According to Yemeni officials, the raid took place in the al-Sirim area in the province of Marib in the early morning hours. Tribal members said explosions were heard in al-Sirim, followed by helicopters and gunfire.
The helicopters landed in the outskirts of the town of Jouba near al-Sirim, which is known as one of al-Qaida's hideouts and which has been targeted by a series of airstrikes in the past month that reportedly killed six al-Qaida militants.
A Pentagon spokesman, Navy Capt. Jeff Davis, said Tuesday that a number of U.S. special operation troops were wounded or injured in the raid, but he would not say how many or provide other details other than to say the U.S. casualties were "ambulatory," or able to walk on their own. He would not say whether the Americans were Navy SEALs or from other elements of U.S. Special Operations Command.
Davis described the target area as a group of "a few" buildings that AQAP was using as a headquarters, and he said it was the deepest that U.S. forces had penetrated on the ground in Yemen. It was the second ground raid conducted by U.S. forces in Yemen this year, he said.
Noting that Central Command announced that at least seven militants were killed, Davis said the number might be higher, given that an AC-130 gunship was called to the scene after a firefight broke out.
"They were met with fire," Davis said of the raiding U.S. troops. "They fired back." The AC-130 gunship was then called in to suppress the hostile fire, he said. Davis would not say whether the U.S. special operations troops were accompanied by partner forces.
According to the officials, there was also bombing in nearby Bayda province. The officials and the tribesmen spoke on condition of anonymity because they were not allowed to talk to reporters. They also did not have any specifics on casualties.
The Marib raid is the second publicly-known U.S. ground deployment in Yemen this year against al-Qaida militants. The United States has stepped up airstrikes as part of a sustained assault on al-Qaida in the Arabian Peninsula in areas of Yemen where it is most active, after a late January special operations raid that resulted in the death of a Navy SEAL.
Washington considers AQAP to be one of the most dangerous branches of the terror network. The January raid also killed 25 civilians, including women and children, and sparked outrage in Yemen. The U.S. military said 14 militants from al-Qaida were killed in the assault and that U.S. service members captured "information that will likely provide insight into the planning of future terror plots."
Al-Qaida has used the chaos of Yemen's civil war following the 2015 launch of the Saudi-led campaign against the Shiite Houthi rebels who seized the capital, Sanaa, and other areas in the country, to expand its footprint and recruitment efforts.
The militant group has also effectively emerged as a de facto ally of the U.S.-backed Yemeni President Abed Rabbo Mansour Hadi and his backers Saudi Arabia and the United Arab Emirates in the battle against the rebels. The United States also supports Saudi Arabia with military advisers, logistics and intelligence, in addition to billions of dollars in arms sales.
Associated Press writer Robert Burns in Washington contributed to this report.