A bomb exploded Monday in a van carrying United Nations employees in a semi-autonomous region of northern Somalia, killing seven and injuring several others, including an American. An Al-Qaeda affiliate claimed responsibility for the attack.

UNICEF reported four of its employees were killed in the bombing. The van was painted white and had UN painted on the side in blue letters. Four others were seriously injured, the U.N. children's agency said.

A senior police officer told The Associated Press that two Kenyans, one Ugandan, one Afghan and three Somalis died in the bomb explosion.

Col. Ali Salad, of the police in Somalia's semi-autonomous Puntland state, says one American, one Sierra Leonean, one Ugandan, one Kenyan and four Somalis were wounded

The blast occured in the town of Garowe.

"It's a dark day - but terrorists must know that the blood they shed will not go in vain," Salad said. "We shall deal with them with an iron hand."

The Al Qaeda-linked terror group Al-Shabaab issued a claim of responsibility, according to its Andalus radio station.

The U.N. special representative to Somalia, Nicholas Kay condemned the attack in a tweet.

 

Somali police official Yusuf Ali told AP that the bomb appeared to have been planted under a seat on the bus and detonated by remote control.

Garowe resident Jama Hashi said he heard a thundering blast inside the bus, which he said was passing near the offices of the U.N.'s food agency when the bomb went off. Human limbs were scattered around the scene of the attack, he said.

Security forces sealed off the area as ambulances carried the wounded from the scene of the blast.

Bomb attacks are not common in the northern parts of Somalia, unlike in the south where al-Shabab militants are waging a deadly war against the Somali government and the African Union forces bolstering it.

Last week at least 10 people were killed in an assault on the offices of Somalia's education ministry. Al-Shabaab's attacks often target the seat of government in the Somali capital, Mogadishu, as well as public places known to be popular with foreigners living in Somalia.

Despite losing a lot of ground in recent times and losing top leaders in airstrikes, al-Shabaab militants are still able to launch attacks in different parts of Somalia and even across the border, especially in Kenya.

Al-Shabaab claimed responsibility for an attack earlier this month at a university campus in northeastern Kenya in which militants killed 148 people, most of them students.

The Associated Press contributed to this report.