The Pentagon has identified the U.S. soldier killed in Somalia as Staff Sgt. Alexander Conrad, 26, of Arizona.
Four other commandos were injured in the attack Friday. The U.S. Africa Command said the injured were being treated by the medical staff at the U.S. Embassy in Kenya. Their names were not released.
Conrad was attached to the 1st Battalion, 3rd Special Forces Group, in Fort Bragg, North Carolina.
The U.S. special operations forces were fighting alongside Somali and Kenyan troops to clear al-Shabab militants from the area "and establish a permanent combat outpost," U.S. Africa Command said.
Witnesses said the attack took place near the town of Sanguni in Jubaland, while the U.S. Somali and Kenyan troops were digging trenches and setting up other defenses.
They said the militants first set off a series of explosions before targeting the forces with heavy gunfire and mortar rounds.
A helicopter was brought in to evacuate the wounded.
The al-Qaida-linked al-Shabab's Shahada News Agency quickly claimed responsibility for the attack via the social media platform Telegram.
"Shabaab al-Mujahideen Movement fighters mounted a fierce attack in a military base of American and Somali forces," the report said, according to a translation by the SITE Intelligence Group.
Despite the attack, U.S. officials say the Somali and Kenyan forces were able to complete the outpost, and that the Somali government will be able to use it to push al-Shabab from the region.
The death of the U.S. soldier in Somalia is the second in the past two years.
In May 2017, a U.S. Navy SEAL was killed near the village of Dar e Salam in Somalia's Lower Shabelle region.
Harun Maruf and National Security correspondent Jeff Seldin contributed to this article.
