KABUL, Afghanistan - A NATO air strike on a compound in southwestern Afghanistan killed a family of six, a local tribal leader said Thursday, the same day the U.S. commander said troops would have to do their jobs "uncomfortably differently" to protect Afghan civilians.

British military officials in the area said they were trying to confirm reports that two women and six children were among the dead. The American military reported that ground forces came under fire from inside the residence before they called in aircraft on Wednesday evening.

Civilian deaths have been a source of friction between President Hamid Karzai and U.S. military commanders and have infuriated many ordinary Afghans, who claim international soldiers use heavy-handed tactics. Gen. Stanley McChrystal has made protecting innocent Afghans a priority since taking command this summer and has ordered troops to limit air strikes.

"We must protect the Afghan people from all threats -- from the enemy, from our own actions," McChrystal said in a speech Thursday in London. "We are going to have to do things dramatically differently, even uncomfortably differently in the way we operate."

The general did not directly address the deaths in Helmand province.

Ghulam Mohammad Khan, a tribal leader, said a local farmer, his wife and four children were among nine dead in the air strike Wednesday evening. He said three guests at the compound also died, but he did not know their identities.

Lt. Col. Nick Richardson, spokesman for British forces in the area, said there were unconfirmed reports that the air strike killed a total of 12 people: six children, two women and four militants.

In Logar province, in eastern Afghanistan, a spokesman for the governor said villagers claimed a U.S. operation overnight killed an innocent shopkeeper and complained that American forces had wrongly detained three civilians. Din Mohammad Darwesh, the spokesman, said villagers were refusing to bury the shopkeeper's body, in order to prove his innocence, and demanding the release of the three men.

Also Thursday, a U.S. military helicopter made an emergency landing after coming under rocket-propelled grenade fire in eastern Afghanistan's Nangahar province, U.S. military spokeswoman Capt. Regina Willis said.

There were no serious injuries, she said.

The incident occurred as President Barack Obama is considering whether to send thousands more U.S. troops to Afghanistan to confront a growing Taliban-led insurgency.

Top military commanders and congressional Republicans are pushing for a troop increase, but there are divisions within the Obama administration on whether to escalate the U.S. presence.

White House officials say it may take weeks more before the president decides whether to overhaul the U.S. strategy in Afghanistan or send more troops.