Kabul (CNN) -- At least 21 people -- including four U.N. personnel, an International Monetary Fund representative and a British contractor -- were killed Friday in a suicide bombing and shootout at a restaurant in Kabul, authorities said.
The suicide attacker's bomb exploded at the restaurant's gate Friday evening. Two armed men then entered the restaurant and started shooting, Afghan Deputy Interior Minister Mohammed Ayoub Salangi said.
Afghan security forces killed the gunmen during a shootout, according to Salangi.
The Taliban claimed responsibility for Friday's attack in an e-mail. It said it was payback for an airstrike in Parwan province that caused civilian casualties this week.
Four of those killed worked for the United Nations, a spokesman for U.N. Secretary-General Ban Ki-moon said. They were among a number of casualties from various "international organizations," in addition to Afghans.
Thirteen foreign nationals were among the dead, said Hashmat Stanikzai, Kabul police chief spokesman.
Christine Lagarde, the IMF's managing director, posted a statement online saying her agency's representative in Afghanistan, Wabel Abdallah, is among the dead. The 60-year-old Lebanese national was named to that position in June 2008.
"This is tragic news, and we at the fund are all devastated," Lagarde said.
Paul Ross, the IMF's mission chief for Afghanistan, remembered Abdallah as a "wonderful, kind man" who was always there for his family, his colleagues and the people of whatever nation he was trying to serve.
"He was modest, he was funny, he was warm," Ross said of Abdallah, who is survived by a wife and daughter. "He was a delight."
Another victim was a British citizen, that country's foreign ministry said. Relatives of the victim -- who was a contractor, not a diplomat -- have been notified. The ministry said she is not being named.
Afghanistan continues to be the site of sporadic violence, much of it blamed on militants tied to the Taliban, which ruled the country before the U.S.-led invasion after the September 11, 2001, terrorist attacks.
The international community has been extensively engaged in Afghanistan for more than a decade both with military troops and nongovernmental organizations. Friday night's attack happened near where many of these NGOs have offices.
Friday night's attack was a "huge shock" to those working there, said Ross, but it won't deter them from continuing their mission.
"I think that many of the people, like Wabel, are dedicated to trying to help countries develop and prosper," Ross said. "That's really part of their life mission statement. And that's what makes them go to places that are difficult to visit."
CNN's Masoud Popalzai reported from Kabul, and CNN's Greg Botelho wrote this story from Atlanta. CNN's Jessica King contributed to this report.