KHARTOUM, Sudan — At least four Unicef staff members were killed and four others were severely wounded in northeastern Somalia on Monday when a roadside bomb exploded near their minibus, a United Nations statement said.

The attack occurred as the staff members were traveling to an office in Garowe from their guesthouse, a drive that normally takes three minutes, the statement said.

The Shabab, a Somali Islamist extremist group linked to Al Qaeda, claimed responsibility for the attack, The Associated Press reported.

The Shabab struck twice last week in the Somali capital, Mogadishu. Gunmen killed a regional lawmaker there on Saturday, and an attack outside the Ministry of Higher Education building on Tuesday left at least 19 people dead. The group also staged an assault on a university in eastern Kenya this month, killing nearly 150 people.