Four doctors - three Kenyans and one Somali - were shot dead in an ambush upon their vehicle about 15 kilometres outside of Mogadishu, a hospital official told dpa on Wednesday.
Their Somali driver and an escort were also killed in the attack, while another doctor from Syria was reported seriously injured.
Their vehicle was first cut off by another car, from which gunmen emerged, firing randomly.
"We do not know the motive behind the attack. This has shocked us and made us very sad. It is very unfortunate to see our colleagues being murdered for unknown reasons," said Abdirahman Mohamed Fiqi, the director of the hospital where the doctors worked.
"The Syrian doctors fled their homeland because of the civil war and came to us voluntarily to help and work with us as doctors," said Fiqi.
"Gunmen with machine guns opened fire on the victims' car as they were traveling today to a hospital outside of Mogadishu for medical issues," a Somali police official said. Investigations were underway.
Islamist militia al-Shabaab regularly attacks convoys and sets off bombs targeting civilians in Somalia.