One official suggested the missiles were launched from Afghan territory just two miles away; the U.S. military and NATO in Afghanistan denied involvement.
The projectiles hit Saidgi, a village in the North Waziristan region, already targeted in operations against militants last year.
A senior military official in the capital, Islamabad, said the dead and wounded were making bombs and had accidentally caused an explosion. But two local intelligence officials said it was a missile attack, and a government official said the projectiles were apparently fired from Afghanistan.
The intelligence and government officials asked for anonymity because of the sensitive nature of the topic, while the military official said he was not authorized to speak to the media on the record.
"We don't have any information that we were participants in" the incident, said Maj. William Mitchell, a spokesman for the U.S.-led coalition. Lt. Col. Angela Billings, spokeswoman for the separate NATO force, said its troops were not involved.
Habib Ullah, the owner of the house, said five missiles hit the building and two empty religious schools nearby. He said the rockets killed four of his guests and brought down the roof of the house.
"I don't know whether these missiles were fired from some plane or not, but those killed in the attack were not terrorists," he told an Associated Press reporter near the scene.
Ullah, who declined to discuss his occupation or answer other questions, said he was staying at another house in the village when the attack happened.
Residents held up shards of metal that they said were remnants of the missiles, and pointed out the damaged roof of one of the schools. The metal pieces carried no identifying marks.
North Waziristan is part of Pakistan's tribal belt, a mountainous zone considered a possible hiding place for Al Qaeda leader Usama bin Laden from where guerrillas launch regular attacks on foreign and government troops in Afghanistan.
Pakistan has deployed 80,000 troops to counter the militants in the tribal areas. It has launched a series of bloody operations and says American troops are not allowed to operate on its soil.
However, weapons fire from the Afghan side sometimes strays over the poorly marked frontier and the U.S. has occasionally launched missile strikes at terror suspects on the Pakistan side.
The schools hit Friday belonged to Maulana Noor Mohammad, a pro-Taliban cleric whose house was hit by an explosion in January 2006 that killed eight people. Tribal leaders complained then U.S. helicopters launched the attack.
Two months later, Pakistani aircraft and troops assailed a suspected Al Qaeda camp in the same village. The government claimed the attack killed 45 people, including a Chechen militant leader.