At least nine people were killed and seven others injured on Monday in an attack on a UN bus in Garowe in north-eastern Somalia, police said.
Those killed included two Kenyans and seven Somali guards, Xinhua quoted the police as saying.
Sources said the bomb might have been planted under a seat of the vehicle and it exploded as the vehicle entered the UN premises in Garowe, around 950 km from the capital Mogadishu.
Special Representative of the UN Secretary General for Somalia Nicholas Kay condemned the attack in his twitter feed.
"I condemn the attack this morning on UN in Garowe. Shocked and appalled by loss of life," Kay tweeted.
"The victims were an integral part of UNICEF's work in Somalia, dedicated to improving the lives of others," the agency said in a statement.
"The vehicle suddenly exploded as it passed by... I ran away since I was at risk," said Nor Ali, an eye witness.
Al Shabab military operations spokesperson Abulaziz Abu Mus'ab said his group was responsible for the attack.
"We carried out the attack in Garowe. We targeted our enemy the UN. We killed and injured many in the attack," he said.
