The casualty figure has not been confirmed.
Taliban insurgents on Friday stormed a UN Immigration office in Kabul, sparking clashes with Afghan troops, police said.
The attack began with a suicide car bombing at the gate of a police directorate, adjacent to the UN office, Hashmat Stanikzai, a police spokesman said.
He said insurgents, including suicide bombers, then stormed the UN office.
At least four Nepalese guards at the UN office were injured, three of them in critical condition, an officer with the IDG company that provides security to UN installations told dpa.
The explosion shattered glass of nearby buildings, including Kabul’s business district.
Mr. Stanikzai said two suicide bombers blew themselves up. There is no report on civilian and troop causalities.
He said at least two more attackers were still holed up in the building.
“We believe the causalities caused by the bombing could be lower since it’s a Friday, a public holiday in Afghanistan, with no civilians commuting in the area,” he said.
The area houses several government and UN offices.
Taliban spokesman, Zabiullah Mujahid, claimed responsibility for the attack.
“A number of mujahideen (freedom fighters) attacked a refuge used by CIA officials in Kabul as well as a department of the Interior Ministry,” said Zabihullah Mujahid, spokesman for the insurgents.
“First, a mujahed detonated his explosives-laden car at the entrance of the CIA building and opened the way for others,” he said, adding that other attackers entered the building and clashed with guards.