There was no immediate comment from the U.S. military.
The attack occurred at around 4 a.m. Sunday, a day after U.S. forces hunting for Taliban insurgents had searched Saghatho village, where the home is located, said Abdul Rahman, chief of Char Chino district in Uruzgan province.
"They were simple villagers, they were not Taliban. I don't know why the U.S. bombed this home. We have informed our authorities," he told The Associated Press by telephone in the southern city of Kandahar.
Maj. Steven R. Moon, a spokesman for the U.S. military in Kabul, had no immediate comment.
The governor of Uruzgan, Jan Mohammed Khan, confirmed Rahman's account that four men, four children and three women were killed in a U.S. bombing.
Also Monday, a U.S. military spokesman said three U.S. soldiers were wounded when insurgents launched a surprise daylight raid on an American base in southern Afghanistan.
The soldiers were hit by shrapnel when about 15 attackers opened fire on the base at Deh Rawood in Uruzgan province early Sunday with rocket-propelled grenades, machine guns and AK-47 assault rifles, Lt. Col. Bryan Hilferty said.
One attacker was killed when American soldiers returned fire.
The injured soldiers, who were flown to the main U.S. military base at Bagram, 250 miles northeast near the capital, Kabul, were in stable condition "and are expected to recover," Hilferty said.
It was unclear whether the attackers were affiliated with the Taliban or other groups who have mounted a wave of assaults on soldiers, government targets and aid workers across the south and east.
At least 45 people, most of them Afghan civilians, have died in violence since the passing of the country's first post-Taliban constitution on Jan. 4.
American bases have also come under attack, usually from misdirected rockets launched under cover of darkness, and Sunday's raid was unusually bold.
Hilferty said Afghan authorities and the 11,000-strong U.S.-led coalition force had control all over the country, but couldn't prevent insurgents from mounting "localized" attacks.
He dismissed Sunday's direct daylight raid as "a sign of desperation. It's not typically what they do. If they attack us like that, we'll kill 'em."
Meanwhile, President Hamid Karzai ordered the release Sunday of more former Taliban fighters, a highly symbolic move that could boost his standing and undermine holdouts from the ousted hardline Islamic regime.
Karzai issued a decree saying all Afghans detained at the northern Sheberghan prison and not considered dangerous should be set free immediately.
It was unclear how many inmates were affected. Local officials said the jail holds more than 400 suspected Afghan Taliban.
The government hopes the move, like the return of millions of Afghans from exile and the release last week of dozens of Pakistanis who fought with the Taliban, will help heal the wounds left by the latest episode in the country's almost quarter-century of conflict.
In an exclusive interview earlier this month with CBS Radio News, Secretary of State Colin Powell called Afghanistan a victory for the United States.
"We have seen considerable progress in Afghanistan with the constitutional loya jirga, and we believe we are on track now to put in place a transitional government in Iraq by the middle of the summer," Powell told Correspondents Dan Raviv and Charles Wolfson.
Powell also expressed hope that Pakistan will soon move to clamp down on Taliban movement across the border with Afghanistan.
"It is an international border and there are certain sensitivities with it," he said. "It is also a very wild area, a very rugged terrain, and it's not the easiest thing in the world to send Americans across into tribal areas where everybody has known everybody in the area for the last thousand years."