Updated

An airstrike on a suspected insurgent camp killed three civilians and four militants in central Afghanistan (search), the U.S. military said Saturday. Afghan security forces opened fire during a celebration in a western city, killing a mother and her daughter.

The shootings, which occurred Friday during celebrations commemorating the fall of Afghanistan's last communist government, drew protesters into the streets of Herat and underscored President Hamid Karzai's challenge to bring stability to the nation.

Demonstrators angered by the killings called for the return of a regional strongman and shouted "down with America."

Police chief Baba Jan said a soldier accidentally opened fire on Friday evening as crowds surged toward an event organized by the Education Ministry (search) in a city park. But interior ministry spokesman Latfullah Mashal (search) said shooting broke out during a row between troops and police.

Jan said eight people were hurt in the ensuing panic.

Officials said a soldier was arrested and officials dispatched from Kabul to investigate.

The U.S. military said Friday's airstrike occurred during a series of attacks over two days against insurgents in Uruzgan, a mountainous province that U.S. and Afghan authorities have failed to pacify despite intense military operations.

"The attack killed one Afghan woman, one Afghan man and a child," the statement said. Two more children were wounded and taken to the U.S. base in the southern city of Kandahar for treatment, the military said in a statement. It didn't say whether U.S. planes carried out the attack or give details of the victims and a spokeswoman had no further details.

Afghan officials and human rights groups repeatedly have complained about civilian casualties in U.S.-led military operations and said heavy-handed tactics could stoke sympathy for militants who have maintained a stubborn insurgency since the fall of the Taliban in 2001.

American commanders insist they modify their operations to try to avoid hurting civilians and accuse militants of using civilians for protection.

The defense ministry said a woman and her daughter were killed during the festivities, but it didn't identify them further.

Witnesses said troops fired more shots into the air to force back rock-throwing protesters enraged by the initial incident.

Karzai expressed condolences to the families of those killed and wounded and ordered "severe punishment" for those responsible, his office said in a statement.

On Saturday morning, hundreds of people marched from the home of former Gov. Ismail Khan to the office of his successor, Sayed Mohammed Khairkhwa, carrying portraits of Khan and calling for his return.

Khairkhwa said that police fired into the air to force the crowds back from his residence and that the protesters had pelted a government building and an army recruitment center with rocks, breaking several windows.

U.N. staff and foreign relief workers in the city were ordered to stay at home or take refuge in bunkers on U.N. compounds.

The violence was the worst in Herat since September last year, when Khan's ouster prompted street riots in which three people died and mobs ransacked the U.N. offices.

Khan, now a minister in Karzai's Cabinet, was a veteran leader of mujahedeen rebels who fought occupying Soviet troops in the 1980s and took power in Kabul on April 28, 1992, before plunging the country into civil war.

U.S. Ambassador Zalmay Khalilzad had pressed for the removal of Khan, whom the central government accused of withholding customs revenue from the nearby Iranian border and whom the U.N. accused of holding up disarmament.