Family members on Sunday blamed US troops, saying soldiers had heard people shooting into the air on Saturday to celebrate a wedding nearby and had fired back from their tanks.
The US military said it had no information about any incident in Zuham village near Miqdadiya, north of Baghdad.
"The attack happened at about 11:30 GMT when the family was in the house," cousin Bashir Ata Allah Salih said.
"The first shell landed in a nearby shop, and the next one inside the house. Two children were blown into pieces. There were five killed and five wounded."
Doctors at a hospital in nearby Baquba, where the wounded were treated, said a sixth person died from her injuries on Sunday morning. Four children under the age of 17 remained in hospital.
Meanwhile, roadside bombs killed seven US soldiers in Iraq and wounded several other people over the weekend, officials said on Sunday.
A bomb exploded late on Saturday killing three troops from the 1st Armoured Division as they patrolled an area in southeast Baghdad, a senior military official said.
Roadside bombs have proved an
effective anti-occupation weapon
"One of our reconnaissance patrols struck an improvised explosive device (IED), the blast caused the vehicle to roll into a canal," the military official said.
A fourth soldier who was wounded died at a combat hospital on Sunday, the Pentagon said.
Hours later, west of the city, a newly arrived US National Guard soldier was killed when the convoy he was travelling in was hit by a separate bomb attack at about 03:00 GMT on Sunday.
"It was sadly yet another roadside bomb," the senior official said.
The soldier, who was due to work with the 1st Infantry Division, died of his wounds while being taken to hospital, the official added.
The attacks bring the number of US soldiers killed in action in Iraq since end of major combat on 1 May to 392.