Gunmen on Tuesday attacked an Afghan memorial service for 16 villagers killed by a US soldier, shooting dead a member of the Afghan military and wounding a policeman in a hail of gunfire.
It was the first deadly violence believed linked to the aftermath of Sunday's killings that the Taliban had vowed to avenge and US officials had warned could lead to a surge in anti-American violence in the war-torn country.
Two of President Hamid Karzai's brothers were in the delegation from Kabul, along with provincial government officials, a local reporter at the scene in the Panjwayi district of southern Kandahar province told AFP.
"There was an armed attack on them from a distance and the firing continued for about 10 minutes," he said.
"Bullets were coming like rain on us," another witness told AFP.
The interior ministry later confirmed that one Afghan soldier died.
"One or more enemy were hiding there. When the delegation arrived they fired -- one soldier is dead and a policeman is injured," ministry spokesman Sediq Sediqqi told AFP.
There was no immediate claim of responsibility but the Taliban had vowed revenge after a US soldier walked off his base in the early hours of Sunday, broke into three houses and killed 16 people -- mainly women and children.
The dignitaries had left the area, with some heading back to Kandahar city about 45 kilometres (28 miles) away, while others remained to continue an investigation into Sunday's shootings, a member of the delegation said.
In the capital, Karzai met families from Kapisa, a province just north of Kabul, and again condemned Sunday's killings as "an oppression" and a "great pain for the people of Afghanistan."
The murders were the latest in a series of actions by troops that have provoked outrage in Afghanistan, and comes weeks after the burning of Korans sparked riots that killed 40 people.
In eastern Afghanistan, about 400 university students chanting "Death to America -- Death to Obama" took to the streets of Jalalabad, in the first protest against the US army sergeant's killing spree.
The crowd set fire to an effigy of US President Barack Obama and blocked the main highway to Kabul before dispersing after about two hours.
Obama has warned the US public against a hasty drawdown from Afghanistan, after a weekend poll said most Americans believe the war is not worth the cost and want an early withdrawal.
On Tuesday, Obama said he met the US ambassador to Kabul, Ryan Crocker, and Afghan mission commander General John Allen on Monday to discuss his strategy for a responsible withdrawal.
"There's no question that we face a difficult challenge in Afghanistan, but I'm confident that we can continue the work of meeting our objectives, protecting our country and responsibly bringing this war to a close," Obama said.
He promised that the culprit would face the "full force" of US law -- wherever the investigation led.
But US Senator John McCain warned the US mission in Afghanistan was "in jeopardy," with Obama's withdrawal announcements and debate over rapid troop drawdowns emboldening Taliban fighters.
The United States and the rest of the 130,000-strong NATO mission in Afghanistan are scheduled to withdraw combat troops by the end of 2014 and hand over responsibility for national security to their Afghan counterparts.
The Afghan parliament and the Ulema Council, the country's highest religious authority, have demanded that the US soldier be tried in public, but the United States has said he will be subject to US military law.
Briefing reporters en route to a visit to Kyrgyzstan, Defense Secretary Leon Panetta said the death penalty could apply. "My understanding is in these instances that could be a consideration," he said.
The US army sergeant was on his first tour of duty in Afghanistan after serving three tours in Iraq, according to US officials.
He left his forward operating base in Kandahar province and turned himself in once back at the base after his murderous rampage, officials say.
The incident has further imperilled Afghan-US relations as the countries try to craft a post-2014 partnership deal.
One major sticking point is the Karzai government's refusal so far to grant legal immunity to American troops -- the same issue that scuppered a US strategic pact with Iraq.
The soldier has not been named. But officials said he is in his 30s, and that the military investigation would look into whether he may have been suffering from mental trauma.
The United States has portrayed the shootings as an isolated incident. But Karzai called them "unforgivable" and the Afghan parliament said "people are running out of patience" over the behaviour of foreign troops in the country.