A Somali police officer says a bomb blast has ripped through a bus carrying U.N. employees in Puntland, a semiautonomous region in northern Somalia.

Yusuf Ali says the bombing took place in Garowe, the regional capital of Puntland, early Monday.

He had no information about casualties.

The bomb was apparently planted under a seat and was detonated by remote control, according to Ali.

No group has immediately claimed the responsibility for the attack.

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.