Somali border town of Balad Hawo near Kenya after al-Shabab detonated a suicide car bomb and then stormed the military base there, the spokesman of the al-Qaeda-linked group told Reuters news agency.
Al-Shabab, which wants to impose its strict interpretation of Islam in Somalia, has carried out frequent past attacks in Mogadishu and elsewhere in its bid to topple the Western-backed government and drive out African Union troops.
"First, a mujahid with a car bomb rammed into the military base and then we stormed it," 24 Somali soldiers were killed in the raid, but a Somali military official put the figure at about 10 dead soldiers the spokesman, Abdiasis Abu Musab, said.
"We were awoken by a suicide car bomb this morning and then fierce battle followed," Major Mohamed Abdullahi told Reuters news agency from the town.
"We killed at least seven militants," and lost 10 soldiers, Abdullahi said. The death toll on both sides could still rise, however, he added.