Alissa J. Rubin and Taimoor Shah / The New York Times – 2012-10-18 00:49:53

KABUL, Afghanistan (October 15, 2012) — A member of the Afghan intelligence service detonated a suicide vest Saturday, killing two Americans and four Afghan intelligence agency colleagues, Afghan and international officials said Monday.

Also on Monday, Afghan officials charged that a coalition strike against a Taliban target had killed three young children — two boys and a girl — from one family over the weekend.

The suicide attack on Saturday morning occurred when a delegation including American coalition members and several members of Afghanistan’s National Directorate of Security arrived to deliver new furniture to the intelligence office in the Maruf district, a remote area of Kandahar Province, according to local Afghan officials.

The attacker, wearing a suicide vest beneath his intelligence service uniform, detonated his bomb shortly after the delegation arrived, killing a former American military officer and an American soldier. The bombing also killed Ghulam Rasool, the deputy intelligence director for Kandahar Province, two of his bodyguards and another Afghan intelligence employee, and set in motion a revenge killing.

Insider attacks have become more common, and have caused about 15 percent of the deaths of coalition troops this year.

This insider attack was the first this year by an intelligence service employee, possibly a guard, to result in the death of international service members, Maj. Martyn Crighton, a spokesman for the international joint command, said.

There have been, however, many insider attacks resulting only in the deaths of Afghan service members, and statistics were not available on whether any of those involved members of the intelligence force, known here as the N.D.S.

Generally the intelligence service is thought to vet its employees more thoroughly than do the Afghan Army and the police, which have far more employees.

In this case the target appears to have been the Afghan agents, Afghan and international officials said.

Haji Malim Toorylai, the Maruf district chief, said, “The man believed he was attacking the N.D.S. delegation; he probably was not aware of the foreign soldiers coming with them.” An official of the NATO-led International Security Assistance Force gave a similar assessment. “It was an N.D.S. attack on N.D.S., and we happened to be in the wrong place at the wrong time,” the official said.

The man who carried out the attack was named Abdul Wali and was from Zirak, a village in Maruf, said Mr. Toorylai. Maruf, the easternmost district in Kandahar Province, is sandwiched between Pakistan’s ungoverned tribal areas and Afghanistan’s Zabul province, a rural desert area where the Taliban have a strong presence.

The former American military officer who was killed was Dario Lorenzetti, a Fort Worth native, The Fort Worth Star-Telegram reported Sunday, describing him as a West Point graduate.

In a tragic coda to Saturday’s story, the suicide bomber’s 9-year-old brother was killed in revenge by the brother of a victim, said Shamsullah, a Maruf local, who commands a guardpost.

“The 9-year-old boy was killed in front of his mother and father,” said Shamsullah. “The parents didn’t know their son Abdul Wali was going to commit suicide.”

The civilian casualty reported by local officials took place in Helmand Province’s Nawa district. The officials said that three children were killed in a NATO strike on Sunday afternoon as they were gathering dung to burn as fuel, a common practice in the desert reaches of southern Afghanistan where there are few trees.

“When we reached the area I saw the three bodies of children, two boys and one girl, ages 8 to 12 years old. They were from the same family,” said Haji Hayatullah, a member of the tribal council in the Nawa district. Their family is in the livestock business and raises goats and sheep on government land, he said.

Mr. Hayatullah added: “They had been collecting the animal dung and were heading home. I saw a sack of dung and another sack that was contaminated with their blood, and I saw three to four holes in the area. It seems the insurgents were digging them to plant mines, but I did not see any men’s bodies.”

The children were identified as Borjan, 12; Sardar Wali, 10; and Khan Bibi, 8, said Haji Abdul Manaf Khan, the governor of the neighboring Marja district. The deaths occurred near the border of the Marja and Nawa districts.

The Marja governor said that NATO forces watched as improvised explosive devices were being planted, and targeted the insurgents planting them. “As a result two I.E.D. planters were killed and the shrapnel killed the three children who were wandering nearby,” he said. Other reports said that three insurgents had been killed.

A spokesman for the international forces, Maj. Adam Wojack, said that the coalition forces were aware of the allegations and that the episode was being investigated. “I.S.A.F. did conduct a precision airstrike on three insurgents in Nawa district, and the strike killed all three insurgents,” he said.

“None of our reporting shows any civilian casualties or any children.”

The United Nations, which tracks civilian casualties, is investigating. While civilian casualties were down 6 percent in the first nine months of 2012, compared with the same period in 2011, they are still occurring in large numbers in the south and east of the country, Georgette Gagnon, the director of human rights for the United Nations mission in Afghanistan, said.

Casualties caused by coalition and Afghan security forces have been “significantly reduced” while those caused by antigovernment forces, including the Taliban, make up an increasing share, she said. According to the most recent United Nations casualty report, the Taliban and other insurgents were responsible for about 80 percent of all civilian deaths and injuries while pro-government forces were responsible for 10 percent.

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