Hamas last night claimed responsibility for the killing of four Israelis in a West Bank drive-by shooting attack 24 hours before President Barack Obama hosts a dinner summit to start the first direct peace negotiations for 20 months.
The shooting near the the Palestinian city of Hebron was said by the Israeli military to have been the most lethal single attack in the West Bank for four years It is the first fatal West Bank shooting since a policeman was killed in June, also outside Hebron.
The Israeli military said the gunmen fired at a car containing two men and two women, one of them pregnant. All were said to be residents of the Jewish West Bank settlement of Beit Hagai in the South Hebron Hills.
The attack occurred after dark on Route 60, a busy main road through the occupied West Bank used by both Israeli and Palestinian motorists. The attack cast an immediate shadow over an imminent 48 hours of intense diplomatic activity in Washington as both the Israeli Prime Minister, Benjamin Netanyahu, and the Palestinian President, Mahmoud Abbas, arrived in the city ahead of meetings before the formal launch of the new direct talks by US Secretary of State, Hillary Clinton, tomorrow.
The Israeli Defence Minister, Ehud Barak, said Israel would "exact a price" for the killings and added: "This was an apparent bid by lowly terrorists to sabotage the attempt to achieve a diplomatic process and to try to hurt the chances of the talks opening in Washington."
The Ynet news service earlier quoted a paramedic who went to the scene, Guy Gonen, as saying the victims were shot at close range in what appeared to be a "well-planned ambush".
Security forces had been prepared for possible violence which might be committed ahead of the talks, as in the past, by Palestinian groups opposed to negotiations with Israel. Hamas, which has no role in the negotiations, has repeatedly criticised Mr Abbas for agreeing to direct talks with Israel. Its armed wing, the Izz el-Din al-Qassam, last night issued a statement saying: "The Qassam Brigades announces its full responsibility for the heroic operation in Hebron."
Hebron is unusual among West Bank cities in that, beside being bordered by the large 42-year-old settlement of Kiryat Arba, it also contains an inner-city enclave which is home to around 800 Jewish settlers.
A US State Department spokesman, P J Crowley, told reporters in Washington: "We are cognisant that there may well be actors in the region who are deliberately making these kinds of attacks in order to try to sabotage the process."
Hundreds of Hamas supporters reportedly demonstrated in support of the attack in one of the faction's strongholds in the town of Jabalya in northern Gaza.