The attack was the latest in a series by suspected Taliban holdouts in recent weeks. The U.S. military has attributed the stepped-up violence to the changing temperature in Afghanistan, which historically sees more military action after the winter thaw.
Also Tuesday, Afghans celebrated the 12th anniversary of the end of communist rule with a traditional military parade, displaying thousands of national army soldiers and police forces seen as the key to establishing stability after decades of turmoil.
Afghan President Hamid Karzai and Defense Minister Mohammed Fahim stood atop old Soviet jeeps newly painted with the white and yellow colors of the national army, saluting Afghans for their victory.
"I congratulate you on the anniversary of the holy war!" Karzai said in an address to the troops.
Meanwhile, word emerged that Afghanistan has carried out its first execution since the fall of the hardline Taliban, putting a bullet to the head of a former military commander convicted of more than 20 murders. Abdullah Shah was executed April 20 in Pul-e-Charkhi jail, the Attorney General's office said.
The violence in Panjwayi, in southern Kandahar province, began Monday, when assailants riding cars opened fire with AK-47s on a building housing the district government, deputy police chief Gen. Salim Khan told The Associated Press.
They then turned their attention to a neighboring building housing an Afghan charity, the Coordination of Humanitarian Assistance, killing two men who worked there.
Six soldiers were wounded in the attack. Khan said two Taliban were killed in a counterattack by his forces. The rest escaped in their vehicles.
The renewed bloodshed has led to fears that security will still not be adequate for historic elections scheduled for September. Afghanistan is in the middle of a registration drive to get citizens signed up for the vote, but it has been beset by delays.
The United Nations has suspended all work in the region after a team of electoral workers was nearly hit by a roadside bomb that detonated as they drove by in Kandahar.
Meanwhile, police in Logar province, just south of the capital, Kabul, arrested three armed men, including one suspected of belonging to forces of Gulbuddin Hekmatyar, a former prime minister who has teamed with the Taliban and al Qaeda to fight the U.S.-led coalition, state-run television reported.
Interior Ministry officials say Zamari is a local commander in Hekmatyar's Hezb-e-Islami army and responsible for attacks in the province. Another suspected, commander, Shahim, escaped. Many people in Afghanistan use only one name.
The executed man, Shah, was a deputy of Hekmatyar.
Serving under a commander named Zardad, he earned the nickname "Zardad's dog," because he was known to have attacked people "like a dog." In the early 1990s, Shah and Zardad reportedly robbed passers-by on the road from Kabul to Jalalabad.
He was first convicted of more than 20 counts of murder in special court proceedings in October 2002.
The government did not acknowledge his April 20 execution until it was revealed by Amnesty International in an e-mailed protest letter Tuesday.
The international human rights group accused the government of carrying out the sentence without affording the accused "even the most basic standards" of fairness, and said the suspect was likely silenced so he could not testify against commanders allied to the government who have allegedly carried out human rights abuses.
Amnesty said Shah was not provided a defense attorney at a secret trial, and that the first judge in his case was dismissed for taking a bribe. The second judge, the group said, came under pressure from the Supreme Court to impose the sentence.
Shah claimed during trial that a confession was obtained under torture, but Amnesty said those charges were not properly investigated.
Jawed Ludin, a spokesman for Karzai, said the Afghan leader signed the death warrant reluctantly, in the interest of justice.
Karzai has personally commuted two prior death sentences, but was compelled by the heinousness of the crime, Ludin said. Shah was convicted of killing one wife by pouring boiling water over her body and murdering his infant daughter by banging her repeatedly against a wall.
Ludin said Karzai ordered a review of the case after Shah was first found guilty, and that a further investigation also confirmed his guilt. He said the death sentence was delayed for months while the government addressed concerns of local and international human rights groups.
At least two other people, suspected Taliban wanted in the November 2003 killing of French U.N. worker Betinna Goislard, have been sentenced to death in Afghanistan. They are appealing the verdict.
In 1979, the former Soviet Union invaded Afghanistan, sending hundreds of thousands of troops to fight Afghan guerrillas — known as mujahedeen or holy warriors.
The Soviets were ousted in 1989, but the pro-Moscow government lasted until 1992.
But the victory only led to more bloodshed when the various Afghan factions turned their guns on themselves in a ruinous civil war that lasted from 1992 to 1996, when the Taliban finally wrested control.