Somalia’s terrorist Shebab militants killed at least 19 people when five gunmen detonated a bomb before storming a popular seaside restaurant in the capital Mogadishu.

Somalia's terrorist Shebab militants killed at least 19 people when five gunmen detonated a bomb before storming a popular seaside restaurant in the capital Mogadishu, police said Friday.

"They killed nearly 20 people, including women and children," Somali police officer Mohamed Abdirahman said, describing it as a "barbaric and brutal attack against innocent civilians".

After a huge explosion, gunmen burst into the restaurant on Thursday evening as diners were sitting down for their evening meal, at the start of Somalia's weekend.

"The fact that they have chosen this location during a weekend night shows how merciless the Shebab militants are," Abdirahman added.

The Al-Qaeda-linked Shebab claimed responsibility for the attack, in which four of their gunmen were also killed, and one captured.

The Shebab, who are fighting to overthrow the internationally-backed government in Mogadishu, carry out regular attacks in the capital.