Kandahar, Afghanistan ? In an unprecedented statement, the Afghan government demanded Tuesday that the United States take “all necessary measures” to avoid civilian casualties following an air attack in which scores of villagers died.

U.S. troops who inspected the hospital in Kandahar where some of the wounded had been taken came under fire late Tuesday as they were returning to the American base outside the city, U.S. military spokesman Col. Roger King said. One soldier was wounded in the foot, he added.

Col. James Wu, center, commander of the Forward Surgical Team from the Kandahar Air base, confers with Lt. Doug Elmoore, right, as they look at the X-rays of Ororakh, 6, while Wu and his medical staff visit and assess the medical needs of the Mir Wais Hospital in Kandahar, Afghanistan, in handling attack victims. Ororakh was among dozens wounded Monday in an attack on the village of Kakarak. Forty people were killed.

In Kabul, the government said President Hamid Karzai “called officials and commanders of the United States forces to his office and strongly advised them of the grave concern and sorrow” over Monday’s attack in Uruzgan province, in which the Afghans say 40 civilians were killed and 100 were wounded.

The statement said Karzai, who relied on U.S. support for his rise to power, insisted that coalition forces “take all necessary measures to ensure that military activities to capture terrorist groups do not harm innocent Afghan civilians.”

Circumstances of the attack remain unclear; a joint U.S.-Afghan team was unable to reach the site Tuesday.

U.S. officials insist American forces were attacking a legitimate target using a B-52 bomber and an AC-130 gunship. Pentagon officials said it appeared gunfire, rather than an errant bomb dropped by the United States, was responsible for the deaths. An AC-130 can fire Gatling guns, cannons and 105 mm howitzers.

At the Pentagon, Gen. Peter Pace said Tuesday a U.S. AC-130 gunship in the vicinity fired on “six individual locations that were spread over many kilometers.” Defense Secretary Donald Rumsfeld said it was too early to determine what happened.

Pace said the gunship attacked several sites where the crew or its American ground spotters saw what they believed was anti-aircraft artillery fire.

Despite the uncertainty, Afghan officials were convinced the United States was to blame for what they believe is the latest in a series of “friendly fire” mishaps. It was the first time Afghan authorities at the national level have issued such a strong statement after such an incident.

Neither Afghan nor U.S. authorities have calculated Afghanistan’s civilian death toll in the war. Although estimates have placed the civilian dead in the thousands, a review earlier this year by The Associated Press suggests the toll may be in the mid-hundreds, a figure reached by examining hospital records, visiting bomb sites and interviewing witnesses and officials.

In the capital, Foreign Minister Abdullah said coalition military operations against al-Qaida and Taliban should continue but the rules for launching attacks “should be reviewed to avoid such incidents.”

Abdullah said four villages were attacked early Monday around the hamlet of Kakarak about 175 miles southwest of Kabul. He said 40 civilians were killed including all 25 members of one family and 100 people were injured, including celebrants at a wedding. “Strong measures have to be taken to avoid such further incidents,” he said.