Four Israelis shot dead near West Bank settlement
Four Israelis have been shot dead in the West Bank, Israeli police say.
Their vehicle came under fire on a road between the settlement of Kiryat Arba and the Palestinian village of Bani Naim, near the city of Hebron.
The military wing of the Palestinian Islamist movement, Hamas, said it had carried out the "heroic operation".
Prime Minister Benjamin Netanyahu said it showed there should be "no compromise" on Israeli security demands at the relaunched direct peace talks.
"The prime minister ordered the security forces to act without diplomatic limitations in order to catch the murderers," his spokesman, Nir Hefetz, said on arrival in the US ahead of Thursday's meeting between Mr Netanyahu, Palestinian Authority President Mahmoud Abbas and US Secretary of State Hillary Clinton in Washington.
"Terror will not determine Israel's borders or the future of the settlements," Mr Hefetz added.
Palestinian Authority Prime Minister Salam Fayyad also condemned the attack, saying it went "against Palestinian interests".
The White House condemned the killings in the "strongest possible terms," adding that all parties must "continue working to achieve a just and lasting peace in the region".
US state department spokesman PJ Crowley said: "There may well be actors in the region who are deliberately making these kinds of attacks in order to try to sabotage the process."'Grave incident'
The attack took place near Bani Naim after dark on Highway 60, a busy route used by both Palestinians and Jewish settlers.
The four victims - two men and two women, one of whom was pregnant - were reportedly shot at from a passing vehicle.
Video footage showed a white estate car standing at an angle on the side of the road, its windows shot out and its doors riddled with bullet holes. Officials said all four victims were from the Beit Haggai settlement.
"This was a terrorist attack and the army is treating it as a grave incident," Israeli army spokeswoman Lt-Col Avital Leibovich told reporters.
It was the first fatal shooting in the West Bank since mid-June, when a police officer was killed, and the most lethal attack in the West Bank in four years, when a suicide bombing killed four people at a settlement.
"Security was stable for the past few years and we hope this will not cause any deterioration," Col Leibovich said.
On its website, the Izz al-Din Qassam Brigades, Hamas's military wing, declared "its full responsibility for the heroic operation in Hebron".
Earlier, Hamas spokesman Sami Abu-Zuhri said the attack had been "a natural response to the crimes of the occupation".
He said it was also proof of a "failure of security co-ordination" between Israel and the Palestinian Authority. Hamas seized control of the Gaza Strip from the Fatah-dominated PA in June 2007.
Hebron, in which some 500 Jewish settlers live in fortified enclaves amid about 100,000 Palestinians, has long been a flashpoint for violence.
The BBC's Wyre Davies in Jerusalem says there was no warning an attack like this would take place, and the incident is likely to strain negotiations this week.
Palestinian Authority President Mahmoud Abbas and Mr Netanyahu will attend a meeting with US Secretary of State Hillary Clinton in Washington on Thursday in what will be their first direct talks in nearly two years.
Before leaving the West Bank, Mr Abbas urged "Israel not to miss this historic opportunity for peace," saying that "if there is only a 1% chance of achieving peace we will strive for it".
Mr Netanyahu meanwhile said he hoped for "a peace based on recognition, security, stability and economic prosperity between the two peoples that will endure for us and our children".
Both sides have agreed to place a one-year time limit on the direct negotiations, but correspondents say prospects of a comprehensive deal are slim, as serious disagreements exist on the core issues.