At least five people, including two of the attackers, have been killed during a raid by armed militants on an army base near the Somali capital’s international airport, a diplomatic memo says.
Earlier, state TV had said security forces were dealing with a “terrorist incident” at the gates to the camp.
A witness said gunmen had forced their way in and started shooting.
State radio reported later that the two attackers had been stopped at the base gates.
“Security Forces have shot dead two armed terrorists who attempted to force their way into the army base near Mogadishu’s Adan Abdulle International Airport on Wednesday and police will give details shortly,” state TV said.
An internal diplomatic security memo seen by Reuters said two security guards, thought to be Kenyan citizens, and a Somali policeman were also killed in the incident while four others were wounded.
Al-Shabab said it was behind the attack, and had fired mortars into the camp, where African Union (AMISOM) peacekeeping troops, United Nations and other international organisations are based.
Abdiasis Abu Musab, an al-Shabab spokesman, said the group’s fighters had gained entry to the base and inflicted casualties but he did not provide any evidence.
Videos and photos shared on social media showed black smoke billowing from an area near the airport runway.
Mahad Hirsi, a witness at the compound, told Reuters he saw the attackers force their way through the gate and start shooting and that “a number of injured AMISOM soldiers (were) lying on the ground”.
Spokespeople for AMISOM and the United Nations’ Somalia office did not immediately respond to Reuters’ calls and messages requesting comment.
A travel agent said flight traffic had been halted due to the gunfire near the airport.
Al-Shabab aims to topple Somalia’s central government and impose its own severe interpretation of Islamic law.