Afghan officials say a suicide attack near United Nations offices in southern Afghanistan has killed at least four people.

Authorities say one attacker detonated a vehicle full of explosives near buildings used by the United Nations refugee agency and the U.S.-based International Relief and Development organization.

After the blast early Monday, at least two gunmen rushed into the area and seized control of an animal clinic. Afghan officials say security forces exchanged gunfire with the men for at least two hours before the attackers were killed.

The Taliban claimed responsibility for the attack. A Taliban spokesman said a U.N. agency was the insurgent group's target.

At least four people were killed in the attack, including a security guard. More than four others were wounded.

United Nations spokesman Dan McNorton told reporters that all U.N. staff had been accounted for.

Monday's attack comes two days after a suicide car bombing in the Afghan capital killed 17 people, including five NATO service members, eight civilian contractors, and four Afghans.

The Taliban claimed responsibility for Saturday's attack. But a Western diplomat told news agencies that it was “very possible” that the attack on a NATO convoy in Kabul was the work of the Haqqani network.

The al-Qaida-linked militant network has carried out a number of attacks on U.S. and NATO troops in Afghanistan. The Haqqani network is believed to be based in Pakistan's North Waziristan tribal region.