MOGADISHU, April 1, 2018 (Reuters) - Islamist insurgents battled for hours on Sunday with African Union (AU) troops after exploding a car bomb outside their base, Somali police, military and the militants said. Al Shabab terrorist group attacked the African Union (AU) peacekeepers' base in the town Bulamarer, 130 kilometers southwest of the capital Mogadishu, around 9 a.m. local time, residents from the area told Reuters. Since withdrawing from Mogadishu in 2011, the al Qaeda-linked group has lost control of most of Somalia's cities and towns. But it still retains a strong presence in regions outside the capital. The insurgents initially detonated two suicide car bombs that hit one AU vehicle and one Somali military vehicle, Somali army major Farah Osman, who is stationed near the AMISOM (African Union Mission in Somalia) base, said. "Then a large number of al Shabaab fighters began firing from under the trees ... it was a hellish battle," he said, adding there was an unknown number of casualties. Terrorists on foot then attacked nearby villages, said Ali Nur, deputy governor of the Lower Shabelle region where the base is located. "They were repulsed, but all these attacks were to stop reinforcement."