The killing, which took place Wednesday in eastern Oruzgan Province, appears to have involved a Hazara commander who is said to have avenged the deaths of two fellow Hazaras by leading an armed group to nearby Pashtun villages and killing at least nine people.

"On Tuesday, two Hazara men were killed by the Taliban," said Matiullah Khan, the provincial police chief. "The next day, meaning Wednesday, this brutal man raided Pashtuns' villages and killed some 9 to 11 villagers," he said, referring to the commander alleged to have carried out the killings. Some reports put the death toll as high as 30.

Most of the Taliban are ethnic Pashtuns and Sunni Muslims; the Hazaras are mostly members of the Shiite branch of Islam, and officials feared the killings could fuel a cycle of revenge. Local officials as well as the Interior Ministry opened investigations, and the governor was traveling to the area on Friday. The Afghan government formally took security responsibility for Oruzgan Province two weeks ago.

Two Afghan officials, including a member of Parliament, asserted that the man who is accused of leading the executions has had a relationship with American Special Operations forces — an assertion that an American spokesman denied. The other Afghan official, the provincial police chief, said the authorities in the area had tried to have the man arrested on past accusations of killing civilians, but that "foreigners" provided refuge for him.

The spokesman for the Special Operations Command, Lt. Col. Todd Harrell, said there were no Special Operations forces in the area and emphasized that it remained unclear if those who were killed were civilians or Taliban.

Pashtuns from the villages where the execution occurred flocked to the center of the remote district of Khas Oruzgan on Friday, shouting for justice, according to local officials who had spoken to the police there.

"Around 200 people, all Pashtuns including some Taliban commanders who were on run, by the name of Shah Wali and Khodaidad, have gathered at the district center as a sign of protest," said Abdul Ali, a member of the Oruzgan provincial council from Khas Oruzgan District, where the killings and the protests took place.

He said the protesters were demanding punishment for the commander, whose name he gave as Shujayee, and were "using bad language against Hazara people, and I am afraid that this will lead to a campaign of revenge against Hazaras."

Khas Oruzgan is remote even by Afghan standards and is a mixed Pashtun and Hazara area where the Taliban have been active for the last several years and have targeted Hazaras in the past. Tensions between the two groups go back decades and the Hazaras were the victims of widespread persecution in Bamian Province and elsewhere when the Taliban ran the country.

There seemed to be widespread confusion among Afghan officials about Commander Shujayee's affiliations, with some suggesting he worked for the Afghan Local Police, who receive a three-week training course from American Special Operations forces and are then deployed to their own villages; they fall under the Interior Ministry's control. Others suggest that he had ties directly to Special Operations units and worked with them rather than with the Afghans. The lack of clarity was a reminder of the number of unofficial groups that operate across Afghanistan and are sometimes confused with the Afghan Local Police.

Making matters more confusing for ordinary Afghans, some of the militias have been hired over the 11-year war by more shadowy arms of the American government, including the C.I.A., to help track down insurgents and have retained an image of invulnerability because of those allegiances. Those too are sometimes described as linked  to Special Operations forces although they may not be. Those who suggested Commander Shujayee had ties to Special Operations forces blamed them for allowing what they called a dangerous man to operate freely.

General Khan, the police chief, said Commander Shujayee was part of a group that had previously "killed 17 innocent civilians and torched half of a big village."

"We referred him to judicial authorities, but foreigners provided refuge to Commander Shujayee, therefore we couldn't find him," General Khan said. "Then he disappeared."

Hajji Obaidullah Barakzai, a member of Parliament from Oruzgan, who said that Commander Shujayee had dumped the dead bodies from Wednesday's executions in a ditch, contended that the commander had 100 armed men and was "closely working with United States Special Operations units."

Gen. Ali Shah Ahmadzai, who heads the Afghan Local Police Command for the Interior Ministry in Kabul, categorically denied that the man was or had been in the Afghan Local Police.

"He is not part of the A.L.P. or any other formal security structure in Oruzgan," General Ahmadzai said. "He wanted to become A.L.P., but since he didn't meet any of the requirements for A.L.P., we rejected him."

More than 14,000 Afghan Local Police members operate across Afghanistan, and Afghan civilians in some areas have accused them of abuses including stealing, harassment and even murder, although the groups are also viewed as an effective ballast against the Taliban.

Human rights advocates said the killings were worrisome. "This needs to be dealt with urgently by the government" and the NATO forces, said James Rodehaver, the acting human rights director for the United Nations office in Afghanistan.

Late Friday, the Taliban released a statement threatening to avenge the deaths of the "innocent and defenseless villagers" and saying that Commander Shujayee had a "green light from foreign forces" for the killings.

Habib Zahori and an employee of The New York Times contributed reporting.