RAMALLAH, West Bank, (AP) – Palestinian security forces arrested more than 150 Hamas members in an overnight sweep throughout the West Bank after the Islamic militant group claimed responsibility for shooting dead four Israelis on the eve of new Mideast peace talks.

With the Wednesday crackdown, the government of Palestinian President Mahmoud Abbas appeared to be trying to send a stern message to both its Hamas rivals and to Israel that it is committed to the new peace talks.

In Washington, Israeli Prime Minister Benjamin Netanyahu said late Tuesday he would not let the shooting derail the negotiations.

The shooting immediately cast a shadow over President Barack Obama’s push for Mideast peace, which was set to formally kick off later Wednesday with a White House dinner. It will be the first direct talks between Israeli and Palestinian leaders in nearly two years.

It also was a vivid reminder that while Hamas is locked out of the peace efforts, it remains a key player in determining the outcome of negotiations. The Iranian-backed group rules the Gaza Strip, one half of the territory claimed by the Palestinians for a future state, and has the power to sabotage negotiations at any moment.

During a visit to a West Bank army base, Israel’s defense minister, Ehud Barak, said the military “will do everything possible to quickly bring the perpetrators to justice.” But he urged residents to show restraint. He called on residents to show restraint. “We are in the midst of a long struggle for our right to live in security under a peace agreement with our neighbors,” Barak said.

A Palestinian security official, speaking on condition of anonymity under official guidelines, confirmed a crackdown was under way, but gave few details. He said the assailants from the shooting had not been found.

Hamas lawmaker Omar Abdel-Raziq said more than 150 members had been detained, and others had been summoned to police stations for questioning. He accused Abbas of trying to please the Israelis.

“These are political arrests,” he said. “They are trying to tell the Israelis that they are capable of doing the job after the attack.”

Abbas, a Western-backed moderate, has carried out frequent crackdowns on Hamas since the Iranian-backed group defeated his forces and overtook Gaza three years ago. In turn, Hamas has frequently targeted members of Abbas’ Fatah movement in Gaza.

Tuesday night’s attack occurred near Hebron, when a gunman opened fire on a passing vehicle, killing all four passengers inside — two men and two women from settlements in the area. The dead included a married couple with five children.

On Wednesday, hundreds of mourners attended a funeral in Beit Haggai, a settlement near Hebron where two of the victims lived.

Hebron has been a frequent flashpoint of violence in the past. Some 500 ultranationalist Jewish settlers live in heavily fortified enclaves in the city, surrounded by more than 100,000 Palestinians.

Hamas, which refuses to recognize Israel’s right to exist and has condemned the new peace talks, quickly took responsibility for the shooting and vowed that more attacks would follow. About 3,000 Palestinians joined a rally in Gaza to celebrate the attack.

The shooting occurred shortly before Netanyahu landed in Washington, where he told reporters that he would not let the violence disrupt the peace efforts. “We will not let terror decide where Israelis live or the configuration of our final borders,” he said.

Netanyahu has said protecting Israeli security would be his top priority as he negotiates the contours of a future Palestinian state with Abbas.

The shooting drew strong condemnations from Abbas’ Prime Minister, Salam Fayyad, who accused Hamas of hurting the Palestinian dream of independence, the European Union and the United States.

“This brutal attack underscores how far the enemies of peace will go to try to block progress” in the talks, White House press secretary Robert Gibbs said, urging the parties to “persevere” in the pursuit of peace.

The violence also added to Netanyahu’s domestic troubles.

As leader of a hardline coalition dominated by ultranationalist and religious parties, Netanyahu is under heavy internal pressure to resume construction in West Bank settlements when a freeze expires on Sept. 26.

Netanyahu imposed the 10-month freeze last November to lure the Palestinians to the negotiating table. Settlers and their supporters in the government want an immediate resumption in construction, but the Palestinians have threatened to walk out of negotiations if building resumes.

Netanyahu has not said what he will do.

Following Tuesday’s shooting, the Yesha Council, which represents the settlers, said it would unilaterally resume construction in West Bank settlements on Wednesday evening.

“The Palestinian leadership speaks softly in English while in Arabic it kills,” said Yesha director Naftali Bennett. He said the settlements protect “the entire West from the onslaught of radical Islam.”

It’s not clear how much the settlers can realistically build before they are stopped by inspectors enforcing the moratorium. Police refused to say how they would respond.

The future of the settlements is one of the thorniest issues in the negotiations.

Some 300,000 Israelis now live in West Bank settlements, along with nearly 200,000 others in east Jerusalem. The Palestinians claim both areas, captured by Israel in the 1967 Mideast war, for their future state.