Rebels from al-Shabaab group attacked a military base in southern Somalia early on Monday, killing at least 10 soldiers and burning three military vehicles, officials said. African Union and Somali troops launched an offensive this year that has driven al-Shabaab out of its last major strongholds. Monday's attack highlights the challenge of halting guerrilla-style raids by the al-Qaeda-aligned group. "Al Shabaab attacked our military forces at 3:00 am" in the Lower Shabelle region, Somali military officer Aden Nur told Reuters. "They killed 10 soldiers and burnt two military vehicles (equipped) with anti-aircraft guns."