New details have emerged about an attack by al-Shabab militants that killed one U.S. soldier and injured four others in southern Somalia last week.Somali officials say the attack occurred just before 2 p.m. local time Friday as U.S., Kenyan and Somali forces set up a combat outpost two kilometers north of the town of Sanguni, in the Lower Jubba region.Mukhtar Abdiweli Moahmed, a unit commander with the Somali forces in Sanguni, told VOA Somali that the soldiers were in the outpost when the militants fired a series of mortars at the camp.“They fired about four mortars rounds from the other side of the [Jubba] river, and one of them hit the U.S. soldier,” he said.The Pentagon has identified the deceased soldier as Staff Sgt. Alexander Conrad, 26, of Arizona. The military’s Africa Command said the four wounded service members received medical treatment and were in the care of the U.S. embassy medical team in Kenya.Sanguni is an agricultural town that sits on the equator. It has been the scene of several confrontations in the past between al-Shabab and Somali forces accompanied by U.S. advisors. Moahmed said due to flooding in the area, the soldiers set up the combat outpost in an open space. He said it was possible the militants could see the U.S. service members before firing the mortar rounds. A second Somali officer who did not want to be named said shrapnel from a mortar hit Conrad in the chest. One of the other U.S. soldiers was hit in the legs by the shrapnel, he said.After firing the mortar rounds, al-Shabab also fired heavy machine guns, wounding a Somali soldier, he said.He said it was not the first time they received mortar fire from al-Shabab. He said the militants fired mortars the night before and again on Saturday, the day after the attack when they fired three rockets. Also on Saturday the militants sent a vehicle-borne improvised explosives device to the camp to detonate, but Somali soldiers intercepted and blew it with a rocket propelled grenade, Mohamed said.The officer said al-Shabab knew the soldiers had moved in to the area. He said they too knew about al-Shabab's presence on the opposite side of the riverbank. “We know their locations and numbers, they know our movements, it’s an open secret,” he said.He said the militants in the area operate in small numbers, and move around to conduct hit-and-run attacks.In a separate incident, at least five Somali soldiers were killed and three others injured Monday in Teed, 30 kilometers (19 miles) north of Huddur, the regional capital of Bakool region, officials said.The mayor of Huddur, Mohamed Moallim Ahmed, told VOA that al-Shabab attacked a Somali military camp at mid-morning today. Al-Shabab said its forces overran the camp but there has been no independent confirmation.Al-Shabab, an al-Qaida-linked radical group, has intensified its attacks during the month-long observance of Ramadan. Despite the attack in Sanguni, 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.Jeff Seldin and Abdulaziz H. Osman contributed to this report.