KABUL, Afghanistan — An operation by Afghan and American forces in the southern Afghan province of Helmand has left at least a dozen civilians dead, officials and residents said on Wednesday, illustrating the plight of noncombatants caught in the middle of the 17-year conflict.
Afghan and Western officials said that Afghan special forces had come under heavy fire overnight during an operation against the Taliban in the Garmsir district and had requested American airstrikes against Taliban fighters.
But on Wednesday, the officials acknowledged that civilians had also been struck. One Western official said that 13 civilians had been killed, in addition to 16 members of the Taliban. Residents of Garmsir put the number of civilians killed at 22.
Ghafoor Ahmad Jawed, a spokesman for the Ministry of Defense, said it had received reports of civilian casualties but could not elaborate on numbers. He said a delegation had been sent to Helmand to investigate.
Sgt. First Class Debra Richardson, a spokeswoman for the American-led NATO coalition in Afghanistan, confirmed that American advisers had been accompanying the Afghan special forces when they came under heavy fire, including by rocket-propelled grenades and machine guns. She said the military routinely investigated accusations of harm against civilians.
“In self-defense, the ground force called an airstrike,” Sergeant Richardson said.
“At the time of the strike,” she said, “the ground force was unaware of any civilians in or around the compound; they only knew that the Taliban was using the building as a fighting position.”
Residents of Garmsir said that most of the civilians killed in the attack were members of a single extended family, relatives of a man named Akhtar Mohammad, whose home in the Kushti area was bombed.
Qudratullah Khan, a relative of Mr. Mohammad, said 22 members of the family — five women, five men and 12 children — had been killed and three others wounded.
“It was around 10:40 p.m. when the helicopters made circles over our village,” he said. “Later, a plane came and bombed Akhtar Mohammad’s home.”
“We buried them in the morning and brought the three wounded to the emergency hospital,” he said. “Akhtar Mohammad was a poor farmer living in a mud house. He was not aware of anything, but the cruel people bombed his home.”
Separately on Wednesday, at least four Taliban attackers entered a base in Kabul belonging to a private security firm, G4S, after detonating a large car bomb at its gates. The explosion was heard across the city.
Col. Bismillah Taban, the police of chief of the district where the attack happened, said six Afghans and a British citizen were killed in the attack, and 27 others — 11 Nepalese, 11 Afghans, and 5 British — were wounded. Most of the casualties came from the initial blast, he said.
Col. Taban said the last of the four attackers were killed nearly 10 hours after the assault begun, just before dawn.
“The police were moving slow because there was a hostage situation inside, where the staff of the firm were stuck in bunkers,” he said. “We rescued 330 people from inside.”
With the long war in Afghanistan continuing its deadly turn, the United Nations has documented more than 8,000 civilian casualties in the first nine months of the year, including 2,789 deaths. The United Nations says that about 25,000 civilian deaths have been documented since it started keeping data systematically in 2009.
In recent months, the United States has actively sought to bring the Taliban to the negotiating table, in the hopes of finding a political settlement to a war that all sides agree cannot be resolved militarily.
But the effort faces hurdles, as the Taliban refuse to meet face to face with the Afghan government until the fighters have first discussed major issues with the United States. The Afghan government insists it needs to lead efforts for peace talks.
American diplomats have repeatedly met with Taliban officials in Qatar in recent months, something that has made the Afghan president, Ashraf Ghani, uncomfortable.
At a donors’ conference in Geneva on Wednesday, Mr. Ghani announced that he had formed a 12-person negotiating team to lead talks with the Taliban, although the insurgents have yet to indicate whether they would meet with them.
“That Afghan government and society must lead and own the peace process,” Mr. Ghani said.
Mujib Mashal reported from Kabul, and Taimoor Shah from Kandahar, Afghanistan. Fatima Faizi contributed reporting from Kabul.