Jerusalem (CNN) -- The Israeli military said Wednesday it is still looking for the perpetrators behind a drive-by attack Tuesday evening that left four people dead, including a pregnant woman.
Meanwhile, Palestinian security officials tell CNN that arrests have been made, but would not specify how many Palestinians had been arrested.
The Israelis were killed near Hebron in the West Bank. The militant wing of Hamas claimed responsibility, officials said.
The shooting occurred near Bani Naim junction, the largely Palestinian territory where Jews have settled in places like Hebron, Israel military spokeswoman Lt. Col. Avital Leibowitz said.
The Israeli military said security forces have constructed road blocks and are searching the area for those responsible.
The deaths of the four Israelis should not be allowed to derail the resumption of Mideast peace talks, former British Prime Minister Tony Blair said.
Blair was speaking as representative of the Middle East Quartet, the four international entities seeking peace in the region. The four members of the Quartet are the United States, Russia, the European Union, and the United Nations.
"I condemn unequivocally the shooting attack in which four Israelis were killed today and extend my condolences to the families of those killed," Blair said Tuesday. "This shocking act was obviously intended to damage the launch of negotiations, but we must not allow extremists to derail the process."
Palestinian Authority President Mahmoud Abbas also condemned the attack. In a statement released Tuesday night, Abbas said the Hamas attack was not a legitimate form of resistance and that any act that targeted either Palestinian or Israeli civilians was wrong.
Guy Gonen, a paramedic who was one of the first people on the scene, said the victims' car was sprayed with bullets.
More than a dozen bullet holes were found in the left side of a white Subaru station wagon.
The attack comes ahead of direct talks scheduled to begin Thursday in Washington between Israeli and Palestinian leaders -- the first such talks since 2008.
Izzedin Al-Qassam Brigades -- the military wing of Hamas -- claimed "complete" responsibility for the attack, according to a statement on its website.
Abu Obeida, a spokesman for the group, confirmed responsibility for the attack in an interview with the Hamas radio station.
Sami Abu Zuhri, a Hamas spokesman in Gaza, congratulated the attackers, saying the attack was a normal reaction to what he called "the crime of occupation." Hamas, which controls Gaza, opposes direct talks and the continued existence of Israel.
"This is a serious incident," Israeli Defense Minister Ehud Barak said in a written statement. "The IDF [the military] and the security forces will do all that is needed to catch these murderers.
"Israel will not allow any terror element to raise its head, and it will collect the price from these murderers and those who sent them. This is an apparent attempt by base terrorists to harm the efforts to move the peace process and to harm the efforts of the talks that are due to begin in Washington."
The incident is a blow to the efforts of Palestinian leaders to prove that they are doing what Israel has most demanded of them -- preventing attacks and providing tough security.
In response to the attack, people from a number of settlements in the north of the West Bank gathered near main road intersections and attacked passing Palestinian vehicles, according to Ghassan Daghlas, the Palestinian official in charge of monitoring settlements in the area.
In addition, some settlers were cutting Palestinian olive trees near Burin village south of Nablus, he said.
In Washington, Secretary of State Hillary Clinton condemned the attack after meeting with Israeli Prime Minister Benjamin Netanyahu.
"This kind of savage brutality has no place in any country under any circumstances," she told reporters.
"The forces of terror and destruction cannot be allowed to continue. It was one of the reasons why the prime minister is here today, to engage in direct negotiations with those Palestinians who themselves have rejected a path of violence in favor of a path of peace."
Netanyahu called the killings "a savage murder" and vowed to punish the killers.
"We will not let terror decide where Israelis live or the configuration of our final borders. These and other issues will be determined in the negotiations for peace we are conducting. And in these negotiations, I will set clearly the security needs that are required precisely to address this kind of terror."
CNN's Kevin Flower, Kareem Khadder and Michal Zippori contributed to this report.