Up to five foreign UN workers and three Afghans were killed in Kabul when armed men stormed a guest house compound used by UN staff early on October 28.
The dawn attack has raised questions and fresh concerns about security for a presidential election runoff due in 10 days.
The UN said nine of its staff were injured in the attack, claimed by the Taliban who said it was the "first step" to disrupt the November 7 presidential runoff. The nationalities of the dead are not known, but officials said one U.S. citizen was among the casualties.
The Taliban said they had targeted the UN because of its role in organizing the election runoff.
"We have said that we would attack anyone engaged in the process and today's attack is just a start," Taliban spokesman Zabihullah Mujahid told Reuters.
Afghan security agents secure the scene of the gunbattle with Taliban militants.
Afghan police said the three attackers, two Afghan security personnel, and an Afghan civilian were also killed.
Aleem Siddique, a UN spokesman in Afghanistan, described the attack as a well-coordinated assault by gunmen on a compound that was separate from any military base.
"Three armed attackers, including at least one suicide bomber, attacked a private guest house here in Kabul which is approved for use by United Nations personnel,” Siddique said. “The gunmen entered the guest house and fighting ensued."
The attackers reportedly wore police uniforms to secure entry into the guest house.
Interior Ministry spokesman Zamarai Beshari told RFE/RL's Radio Free Afghanistan that the area where the attack took place was considered relatively safe, and that there were not many security forces in the neighborhood.
"We have already started our investigations and other immediate details related to this case will be disclosed soon," Beshari said.
Later, the bodies of three of the suspected suicide bombers, apparently ripped apart when they detonated their explosives, could be seen lying inside the compound.
Abdul Ghaim, a policeman at the scene, told Reuters: "We think [the militants] are Pakistani."
In New York, UN Secretary General Ban Ki-moon said the attack would not deter the UN from its mission in Afghanistan.
"We stand by the people of Afghanistan today and we will do so tomorrow," Ban said. "We will of course review our security procedures as we do regularly for the Afghanistan mission as a whole. We will take all necessary measures to protect our staff.”Second Attack
In another sign of the growing reach of militants, rockets also were fired at a foreign-owned luxury hotel near the presidential palace in Kabul on October 28, forcing more than 100 guests into an underground bunker.
Smoke rises from a UN guest house during a gunbattle in Kabul.
The Kabul attacks come a day after eight U.S. troops were killed in southern Afghanistan in the deadliest month for U.S. forces since the start of the war eight years ago.
Meanwhile, the White House announced President Barack Obama is to meet U.S. military chiefs on October 30 to discuss whether to send more troops to Afghanistan.
The White House said the meeting with the Joint Chiefs of Staff is to be among the last in the decision-making process.
Ahead of that decision, "The New York Times" reported that the brother of Afghan President Hamid Karzai had been getting regular payments from the Central Intelligence Agency and was a suspected player in Afghanistan's opium trade.
Ahmed Wali Karzai was quoted as denying the report and the CIA neither confirmed nor denied the reported payments.Across The Border
The Kabul attacks took place as a bombing in the northwestern Pakistani city of Peshawar killed at least 90 people
Peshawar, a teeming metropolis, is a gateway to Pakistan's northwest tribal belt -- where the military is continuing a major offensive against Pakistani Taliban militants blamed for some of the worst carnage in the region.
At the same time, U.S. Secretary of State Hillary Clinton arrived in Islamabad vowing a new page in U.S.-Pakistan relations. The deadly explosion in Peshawar occurred just as she was beginning her talks with Pakistan's Foreign Minister Shah Mehmood Qureshi.
Clinton condemned the attacks in Afghanistan and Pakistan, which she called "cowardly."
"The United States remains steadfast in its support for the United Nations and its vital work to help the Afghan people," she said, adding that 20 Americans had died in Afghanistan in recent days.RFE/RL's Radio Free Afghanistan contributed to this report; with agency reports