Four Israelis were killed in a shooting attack near the West Bank town of Hebron on Tuesday, an Israeli army spokeswoman told Xinhua.

A military wing of the Palestinian Islamic Hamas movement has claimed responsibility for the attack.

At around 7 p.m. (1700 GMT), gunmen, possibly in a passing vehicle, opened fire on four civilians -- two men aged 25 and 40 respectively, and two women of similar ages, one of them pregnant - - traveling in a vehicle near the Israeli settlement of Kiryat Arba.

The gunmen stopped nearby after spraying the vehicle with gunfire, and repeatedly shot the victims at close range, according to Israel's Channel 10 television.

Medical sources said that the victims are a couple who lived in the nearby settlement of Beit Hagai, and two hitchhikers.

Large Israeli army and police forces spread out in hot pursuit of the gunmen, and used a helicopter in the chase. Roadblocks have been erected throughout the area in hopes of capturing the assailants.

The shooting, appearing to be a planned ambush, happened on the eve of a would-be breakthrough in Israeli-Palestinian peace process.

Earlier Tuesday, Israeli Prime Minister Benjamin Netanyahu left for Washington D.C. to attend a U.S.-proposed peace summit, which is slated to kick off on Thursday.

Israeli officials said Netanyahu has been alerted of the shooting, en route to the White House for direct talks on Wednesday with Palestinian President Mahmoud Abbas.

Netanyahu conferred with Defense Minister Ehud Barak from his plane, which is expected to land in Washington in several hours.

Abbas was reportedly meeting with U.S. Secretary of State Hillary Clinton when the attack took place.

Neither leader has yet released a statement in response to the deadly shooting.

Israeli residents in the area told Xinhua that they have noted an increased police and military presence, including temporary roadblocks and inspections of passing Palestinian vehicles in the last week.

The measures may be a response to Israeli army chief, Lt-Gen. Gabi Ashkenazi's instructions to step up security measures in the run-up to the summit, in hopes of heading off such an attack.

In June, a similar shooting attack in the area killed a police officer and wounded two others.

Palestinian National Authority security forces have joined the investigation into the attack, reported the Palestinian news agency Ma'an.

Earlier, the Palestinian Islamic Hamas movement praised the shooting, calling it "an expected response to the crimes of the Israeli occupation," but denied any involvement.

"The armed operation in Hebron emphasizes the presence of the Palestinian resistance in the West Bank" despite Palestinian security programs "that aim at cutting up the resistance," Hamas' military wing Ezz El-Deen Al-Qassam Brigades said in a brief statement.

Israeli responses were divided, with one government minister saying the talks should go on despite the shooting.

"I do not think that we need to give a prize to the murders not to hold talks," Education Minister Gidon Sa'ar said, but added "as we see an Israeli hand extended to peace, we see a murderous response on the part of Palestinians."

Right-wing Knesset member Michael Ben-Ari said the attack was " a reminder to Prime Minister Binyamin Netanyahu who his partners are."

"The Likud government's negotiations with the terrorist Abu Mazen (Abbas) are an energy boost to murderousness and terror. The blood of those harmed is upon the head of the Likud government," The Jerusalem Post newspaper quoted Ben-Ari as saying.