A suicide bomber blew himself up at the entrance of a popular restaurant filled with affluent foreigners and Afghans Friday, while two gunmen snuck in through a back door and sprayed gunfire across the busy dining room, killing 16 people.

The Taliban claimed responsibility within an hour of the attack against the Lebanese restaurant, La Taverna du Liban, serving as a reminder that although violence in the capital has dropped in recent months, insurgents remain capable of carrying out attacks inside the most heavily guarded areas.

Security officials said the assault began with the suicide bomber detonating his explosives at the front door of the restaurant, located in an area housing several embassies, non-governmental organizations and the homes and offices of Afghan officials. As chaos ensued, the two other attackers rushed in through the kitchen and began shooting. They were later killed by security guards in a gunbattle that lasted more than an hour, officials said.

The initial blast appeared to have been powerful. It was heard miles away and shook windows in the immediate neighborhood, a district that is home to numerous embassies and shops that serve Western aid workers, journalists and other foreign civilians who live in the city.

Kabul police chief Gen. Mohammad Zahir Zahir said the 16 people killed were all inside the restaurant. He said foreigners and Afghans were among the dead. Officials said at least four other people were wounded.

The brazen episode was the deadliest attack in Kabul since last June, when a car bombing outside the Supreme Court building killed 17 people and wounded 39 others.

The International Monetary Fund’s representative in Afghanistan, Wabel Abdallah, was among those killed, IMF chief Christine Lagarde said in a statement. The 60-year-old from Lebanon was appointed to the position in 2008.

Four U.N. employees who “reportedly could have been present in close proximity to the scene of the attack” remained “unaccounted for,” said Ari Gaitanis, a spokesman for the U.N. mission in Afghanistan. The mission said in a statement that some of its staff “may be among the dead” and was verifying the status of personnel in Kabul.

“I strongly condemn the targeting of civilians in any form, and, in particular, the continued use of suicide bombers,” said the Secretary-General’s Special Representative for Afghanistan, Jan Kubis. “This violence is unacceptable and must stop immediately.”

Britain’s Foreign Office confirmed late Friday that a British national was among the dead.

In Washington, State Department spokeswoman Jen Psaki said the U.S. condemns “this despicable act of terrorism in the strongest possible terms.” She said that information about the attack is still coming in, but all U.S. Embassy personnel were accounted for.

Deputy Afghan Interior Minister Ayoub Salangai said in a tweet that the dead included four women.

The restaurant, like most facilities that are frequented by foreign diplomats, aid workers, journalists and businessmen in the war-weary country, has no signs indicating its location and is heavily secured. It sits on a small side street just off a bumpy semi-paved road in a house with low ceilings and an enclosed patio but no windows.