The Israeli military said a Palestinian has infiltrated a Jewish West Bank settlement and killed five people.
Israeli media is reporting that the dead are all members of the same family - parents and three children.
The military said it is sweeping the area in search of the perpetrator and has set up checkpoints throughout the West Bank.
The overnight attack early today in the northern West Bank settlement of Itamar is the first of its kind in years. It marks a rare outburst of violence during a relatively calm period.
Itamar is home to some of the West Bank’s most fervent settlers. The attack took place in the middle of the night against a religious community on the Jewish Sabbath.
Those killed were a husband and wife, an 11-year-old, a three-year-old and a baby girl.
The dead were discovered by a 12-year-old family member who was returning from a youth group function.
The Israeli military said “Palestinian terrorists” had infiltrated the settlement.
Palestinian Prime Minister Salam Fayyad condemned the attack.
“Violence does not justify violence, we condemn it completely, whoever does it and whoever the victims are,” Fayyad said.
The attack happened on the Jewish Sabbath when the observant are prohibited from working and most physical activity, instead spending the day in prayer or rest.
Footage from the scene broadcast on Israeli media showed children’s toys covered in blood and furniture tipped over.
Israeli media said two young children were asleep in another part of the house and survived.
The Al Aqsa Martyrs’ Brigades, a mostly defunct Palestinian militant group, took responsibility for the attack. However, it was not clear if they really did it or were just taking credit. The Brigades frequently take credit for attacks they didn’t do in hopes of raising their profile.
The Israeli military set up checkpoints and searched the area. Residents of the nearby village of Awarta said Israeli soldiers had surrounded a building and made some arrests.
Defence Minister Ehud Barak convened security and intelligence personnel overnight and conferred with Prime Minister Benjamin Netanyahu, his office said in a statement.
Israeli Foreign Minister Avigdor Lieberman said he would file a complaint with the UN over the attack and that he expects “worldwide condemnation of the satanic murder of an entire family”.
The attack is the first against settlers in months and the first of its scope in years, marking a rare outburst of violence during a relatively calm period.
Peace talks between the two sides collapsed last year over disputes over Israeli settlements in the West Bank, territory Palestinians envision as part of their future state.
“Now maybe the international community that condemns us all the time will understand who we are dealing with here, in every peace agreement they want us to sign, they need to understand who is on the other side,” said Danny Danon, a hawkish member of Israeli Prime Minister Benjamin Netanyahu’s Likud party.
Itamar is a small, isolated settlement in the northern West Bank that has rocky relations with the nearby Palestinian towns and villages.
The attack was reminiscent of a similar one against Itamar in June 2002, during the height of the violent Palestinian uprising, when a gunman burst into the home of a family and opened fire.
The mother of the family and three of her children were murdered. Another two children were seriously injured and a local security official was shot to death as he tried to help.