Somalia’s al Shabab Islamic extremists launched an attack on African Union troops in the country’s south, killing four Ugandan peacekeepers, said Ugandan army spokesman Brigadier Richard Karemire.

Four others Ugandans were injured, Brig Karemire said.

At least 22 of the attackers were killed and the rest were repelled, he said.

The attack started when two suicide car bombs exploded at the entrance to the heavily fortified base in Bulo-Marer, an agricultural town in Somalia’s Lower Shabelle region, said Somali army Colonel Ahmed Hassan.

Nearly 100 fighters firing propelled grenades and machine guns attacked the base occupied by the Ugandan soldiers.

“That attack was repulsed but several soldiers have lost their lives to the bomb,” said Col Hassan.

Residents reported explosions and sustained gunfire, sending hundreds of terrified villagers to the bush.

“We had a frightening day but the situation is calm now,” said Nur Yusuf, a local elder by phone saying that African Union and Somali troops were patrolling the town in the evening.

Somalia’s Islamic extremist group, al Shabab, claimed responsibility for the attack.

Al Shabab, which is fighting to impose Shariah law across Somalia, was pushed out of the capital, Mogadishu, and other major urban cities more than two years ago, but the group still carries out suicide attacks across Somalia.