KABUL (AP) - Villagers dug dirt graves Wednesday to bury what the international Red Cross said were dozens of Afghans - including women and children - killed in American bombing runs. A former Afghan government official said up to 120 people may have died.
If so, it would be the deadliest case of civilian casualties since the 2001 U.S.-led invasion.
Secretary of State Hillary Rodham Clinton said the U.S. "deeply, deeply" regretted the loss of innocent life, and the U.S. military dispatched a brigadier general to investigate the deaths in two villages in western Afghanistan's Farah province.
The top U.S. and NATO commander in Afghanistan, Gen. David McKiernan, voiced doubts about whether it was an American airstrike that caused the tragedy.
McKiernan said U.S. military personnel had come to the aid of Afghan forces who may have been ambushed by Taliban militants on Sunday. He said the Taliban beheaded three civilians, perhaps to lure police.
"We have some other information that leads us to distinctly different conclusions about the cause of the civilian casualties," McKiernan said. He would not elaborate but said the United States was working with the Afghan government to learn the truth.
A senior U.S. defense official said late Wednesday that Marine special operations forces believe the Afghan civilians were killed by grenades hurled by Taliban militants, who then loaded some of the bodies into a vehicle and drove them around the village, claiming the dead were victims of an American airstrike.
A second U.S. official said a senior Taliban commander is believed to have ordered the grenade attack. The officials spoke on condition of anonymity because they weren't authorized to release the information.
Two other senior defense officials said the grenade report comes from villagers interviewed by U.S. investigators who went to the site, but there is no proof yet that the report is right.
If correct, it would be the first time the Taliban has used grenades in this way, presumably to mimic the effect of a bombing.
Afghan President Hamid Karzai called the deaths "unacceptable," speaking only hours before his first face-to-face meeting with President Barack Obama at the White House. Karzai has long pleaded with the U.S. to minimize civilian deaths during its operations, contending that such killings undermine support for the fight against the Taliban.
Obama's national security adviser, James Jones, said Obama led off his meeting with Karzai by expressing great sympathy over the loss of life and pledging that investigations into what happened in the bombing will be "pursued aggressively."
Karzai did not ask that U.S. airstrikes be suspended or reduced in intensity pending the outcome of the investigation, Jones said.
The number of civilians killed in Afghanistan's worsening conflict jumped 40 percent to a new high last year, though more than half of the deaths were inflicted by Taliban insurgents and other militants, the U.N. has reported. A record 2,118 civilians died from violence last year, up from 1,523 the previous year.
Associated Press photos showed villagers burying the dead in about a dozen fresh graves early Wednesday, while others dug through the rubble of demolished mud-brick homes.
On Tuesday, an international Red Cross team in Farah's Bala Baluk district saw "dozens of bodies in each of the two locations that we went to," said spokeswoman Jessica Barry.
"There were bodies, there were graves, and there were people burying bodies when we were there," she said. "We do confirm women and children."
Afghan police have said that 25 Taliban died in the fighting, which began Monday and lasted until early Tuesday.
It was unclear whether they were among the dozens of bodies witnessed by the Red Cross.
Tribal elders called the Red Cross during the fighting to report civilian casualties and ask for help, said Reto Stocker, the agency's head in Afghanistan.
"We know that those killed included an Afghan Red Crescent volunteer and 13 members of his family who had been sheltering from fighting in a house that was bombed in an airstrike," Stocker said.
A Western official said Marine special operations forces called in the airstrikes. The U.S. troops responded to a call for help from Afghan security forces who had been attacked by Taliban militants Monday afternoon. The official spoke on condition of anonymity because he wasn't authorized to release the information.
"Because of the overwhelming firepower coming in by the enemy, they called in airstrikes," said Capt. Elizabeth Mathias, a U.S. military spokeswoman.
Villagers said they gathered children, women and elderly men in several compounds near the village of Gerani to keep them away from the fighting, but the compounds were later hit by airstrikes.
Taliban militants often take over civilian homes and launch attacks on Afghan and coalition forces. U.S. officials say the militants hope to attract U.S. airstrikes that kill civilians, thereby giving the Taliban a propaganda victory.
After a massive case of civilian casualties in the village of Azizabad last August, McKiernan ordered forces to consider backing off from a fight if commanders thought civilians were in danger. Afghan officials and the U.N. say 90 civilians died in Azizabad; the U.S. says 33 died.
Mohammad Nieem Qadderdan, a former district chief of Bala Buluk who visited the site of this week's battle, said 100 to 120 people were killed. If 100 civilians died in the fight, it would be deadliest case of civilian casualties since the 2001 U.S.-led invasion.
"People are still looking through the rubble," Qadderdan said. "We need more people to help us. Many families left the villages, fearing other strikes."
Provincial authorities have told villagers not to bury the bodies, but instead to line them up for the officials conducting the investigation, Qadderdan said.
Karzai ordered an investigation, and the U.S. military sent a brigadier general to Farah to head a U.S. probe, said Col. Greg Julian, a U.S. spokesman. Afghan military and police officials were also part of the team. The team did not reach the site of the bombings Wednesday but hoped to on Thursday.
Opening a meeting with the presidents of Afghanistan and Pakistan at the State Department, Clinton said any loss of innocent life was "particularly painful."
Karzai thanked Clinton for "showing concern and regret" and said he hoped the countries "can work together to completely reduce civilian casualties in the struggle against terrorism."
State Department spokesman Robert A. Wood said later that Clinton's remarks were offered as a gesture, before all the facts of the incident are known, because "any time there is a loss of innocent life we are going to be concerned about it, and we wanted to make that very clear."
Kai Eide, the senior U.N. envoy in Afghanistan, said avoiding civilian casualties is a "particularly big challenge" given the increased number of U.S. forces arriving in the country this summer.
On Wednesday, Defense Secretary Robert Gates landed in Kabul to meet with troops as the U.S. prepares to send 21,000 more forces to bolster the record 38,000 already in the country to battle an increasingly violent Taliban insurgency.
Associated Press reporters Fisnik Abrashi, Heidi Vogt and Rahim Faiez in Kabul, Kevin Maurer in Wilmington, N.C., and Matthew Lee in Washington contributed to this report.