The Israeli army has launched a large-scale offensive in the Gaza Strip, in what is being seen as a fresh blow to US efforts to push a new peace plan for the region.
Palestinian boys run for cover as Israeli tanks enter Beit Hanoun
About 50 tanks and helicopters entered the northern town of Beit Hanoun, leaving four Palestinians dead - including a 12-year-old boy, according to Palestinian witnesses.
The Israelis say the raid was launched after dozens of mortar bombs and rockets were fired at Jewish settlements in the Gaza Strip and the southern Israeli town of Sderot in recent days.
The incursion comes on Nakba, which Palestinians describe as "Catastrophe day" - when they mark the anniversary of the displacement that accompanied the creation of the state of Israel in 1948.
It also comes two days before the first meeting between Prime Minister Ariel Sharon and his counterpart Mahmoud Abbas - widely known as Abu Mazen.
Thursday's raid on Beit Hanoun was the largest Israeli operation in recent months.
'Left to die'
Witnesses say Israeli bulldozers destroyed four homes belonging to suspected militants.
They say the Palestinians killed in the raid included two men and a 12-year-old boy.
According to doctors, the boy was left to bleed to death, as Israeli troops prevented paramedics from reaching the scene.
The Israeli army said it knew nothing about the circumstances of the boy's death.
On Nakba day, Palestinians traditionally attend
rallies holding banners with the names of villages they or their family fled in 1948.
"It seems they [Israeli soldiers] are also commemorating the Nakba with us, but in their own bloody way," a Beit Hanoun resident told Reuters news agency.
Israeli tanks were also reported in the nearby town of Beit Lahiya and the Jabaliya refugee camp, where Palestinians said one man had been killed.
There were clashes on Wednesday in the Gaza Strip, where the Israeli army shot dead five Palestinians.
Observers say the renewed violence suggests the international peace plan is having no impact.
ROADMAP MAIN POINTS
Phase 1 (to May 2003): End of terrorism, normalisation of Palestinian life and Palestinian political reform; Israeli withdrawal and end of settlement activity; Palestinian elections
Phase 2: (June-Dec 2003) Creation of an independent Palestinian state; international conference and international monitoring of compliance with roadmap
Phase 3 (2004-2005): Second international conference; permanent status agreement and end of conflict; agreement on final borders, Jerusalem, refugees and settlements; Arab states to agree to peace deals with Israel
The plan - known as the roadmap - was drawn up by the United States, Russia, the European Union, and the United Nations.
It outlines a process that is supposed to begin with the end of Palestinian attacks and Israel's withdrawal from Palestinian territories.
Under the plan, a Palestinian state is due to be established by 2005.
However Mr Sharon has said that in its present form the roadmap does not sufficiently address Israel's security concerns.
On Tuesday he said the key question of Jewish settlements was not up for imminent discussion.
The prime minister added that he would not be put under pressure on this issue when he visits Washington to discuss the peace process next week.
On Saturday, Mr Sharon is due to meet Abu Mazen, for the first Israeli-Palestinian summit in almost three years.
The Palestinian prime minister has said he will not move against militants unless the Israelis drop their reservations about the roadmap.