Gunmen marched into a remote mountain village in Mexico on Friday and killed 11 members of a family, including two children, apparently over "personal conflicts", authorities said.
Five women, four men and two girls were killed in the pre-dawn attack in El Mirador, a community in central Puebla state, near Oaxaca.
Two other girls were wounded in the attack and were taken to a hospital.
Witnesses identified two assailants and recognised one of them as a man who allegedly sexually abused one of the dead women nine years ago, resulting in the birth a boy, according to the state prosecutor's office.
The woman's current partner, who was killed, was stabbed several times and had "more wounds than the other" victims, the office said in a statement.
The two assailants fled toward neighboring Oaxaca state. Authorities in both states are searching for them but the hamlet is so remote that it is only accessible on foot.
"It was an act of revenge," said Vicente Lopez de la Vega, mayor of Coxcatlan, the municipality that oversees El Mirador.
"To kill 11 people like that, you don't have feelings. It's alarming," Lopez de la Vega said.
The prosecutor's office said the gunmen "arrived on foot where the family was located, fired several times and left on foot."
Pistol and rifle bullet casings were found at the scene.
Government officials, who spoke on condition of anonymity because they was not authorized to speak publicly, said the attack took place inside one home.
Two witnesses have been placed under state protection.
An official at the prosecutor's office had earlier said that authorities were investigating whether the crime was related to organized crime or a family dispute.
The village is inhabited by Evangelicals who broke away from another community of Catholics, El Potrero. But the mayor said the two villages respected each other.
"It's a community in harmony, but things change. There's immigration. Many go north of the country and to the United States. Sometimes when people come back the harmony is lost," Lopez de la Vega said.
It is the latest murder to rock Puebla, a region that has been relatively spared the drug violence that has plagued other parts of Mexico.
In March, an undetermined number of human remains were found in various acid containers in a rural area.
In April, four bodies were found inside a burnt car near Veracruz, an eastern state beset by murders and disappearances linked to drug cartels. Two of the bodies belonged to sisters of a jailed Zetas drug cartel member, Veracruz authorities said.
That same day, three other bodies were found in the same area near a facility of state-run oil firm Pemex.
Late last month, four people died when gunmen linked to fuel thefts opened fire in the village of La Purisima, a region where rival gangs seek to control such illegal pipeline taps.
Puebla has also seen a spate of mob lynchings of crime suspects.