Armed Palestinians in wetsuits and flippers emerged from the Mediterranean and fired toward a beachfront Israeli settlement in the Gaza Strip, the army said Friday. Two attackers were killed, and a third was wounded and fled.

The Islamic militant group Hamas claimed responsibility for the attack on the Tel Katifa (search) settlement in Gaza. Hamas has threatened to carry out attacks on Israelis to avenge the assassination of its founder, Sheik Ahmed Yassin (search).

In a farewell video, two attackers posed in their wetsuits, with oxygen tanks strapped to their backs and goggles pulled above their foreheads. The video also contained footage of a training session in which two men charged toward a rocky cliff, firing assault rifles. The settlement attack is the first of "earthshaking operations to come," a Hamas leaflet said.

In the West Bank town of Bethlehem, Israeli soldiers shot and killed a Palestinian in a brief clash with about a dozen youths hurling stones near the Rachel's tomb (search) holy site, according to hospital officials and witnesses.

Thousands of Hamas supporters marched Friday in the West Bank towns of Nablus and Ramallah, threatening revenge. In the Nablus, the protest was led by about 200 men in masks and military-style dress. At one point, they torched a large model of an Israeli bus.

In the nearby Balata refugee camp, a Palestinian militant was killed when a car he was driving exploded. Palestinian security officials said the car carried explosives that apparently blew up prematurely. The blast killed Ahmed al-Abed of the Al Aqsa Martyrs' Brigades (search), an armed group linked to Yasser Arafat's Fatah movement.

In the Gaza attack, the assailants came ashore late Thursday. From the beach, they fired assault rifles and rocket-propelled grenades toward the Israeli army post guarding the settlement, and soldiers returned fire.

Ari Odes, a Tel Katifa resident, said he and his wife were driving toward the settlement when they heard shooting. Moments later, he saw the attacker on the road, aiming at the car, Odes told Israel Radio.

"I pulled my head down and tried to aim the wheel so as to run him over, but he jumped onto the shoulder of the road and I drove into the settlement," Odes said. "There was a second terrorist who shot massive fire at the gate of the settlement and the outpost."

An Israeli army officer said the Israeli navy spotted three men swimming toward the beach and that two approached the settlement. A third was wounded and footsteps indicated he fled into the sea, said the officer, identified only as Lt. Ayelet.

Soldiers found rocket-propelled grenade launchers, assault rifles and explosives on the beach, along with flippers. The military believes the attackers were trying to build a bomb to attack the settlement, she said.

Tensions have increased significantly since Israel assassinated Yassin on Monday.

At the United Nations, the United States on Thursday vetoed a Security Council resolution condemning Israel for the killing. The U.S. ambassador complained the text did not mention Hamas attacks against Israelis.

Palestinian Cabinet minister Saeb Erekat said the U.S. veto will be seen by Israel "as an encouragement to continue the path of violence, escalation, assassination and reoccupation."

At Friday noon prayers at Jerusalem's Al Aqsa Mosque, Islam's third holiest site, a cleric harshly attacked the United States. "The United States is not the sponsor of peace, it is the sponsor of international terrorism, and this veto is a green light to continue the assassinations," said the cleric, Yousef Abu Sneineh.

Israel's tightened security has foiled several attacks in recent days. On Wednesday, soldiers stopped a 16-year-old Palestinian, Hussam Abdo, with a bomb vest strapped to his body at a crowded West Bank checkpoint, setting off a tense encounter with soldiers.

Abdo remained in Israeli custody Friday, but military sources said he might be released soon. The Al Aqsa group denied recruiting the youth, although his uncle, Jihad, said the boy's ID card had the words "Al Aqsa Brigades" scribbled on it. It is customary for attackers to leave their ID card with the group that dispatches them, for a subsequent claim of responsibility.

Abdo's family said he was gullible and easily manipulated, and relatives demanded that militants stop using children for attacks.

"It is forbidden to send him to fight. He is young, he is small, he should be in school. Someone pressured him, maybe because they killed Ahmed Yassin," wailed Abdo's mother, Tamam.

Also Friday, Israel's vice premier said Israel is not seeking U.S. approval of its plan to withdraw from most of the Gaza Strip, although it would like to coordinate certain moves with Washington.

Vice Premier Ehud Olmert, a confidant of Prime Minister Ariel Sharon, told Israel Army Radio that Israel is not demanding U.S. guarantees or public statements in exchange for a unilateral withdrawal.

Sharon's aides initially suggested that in exchange for withdrawing from Gaza, Israel is seeking U.S. approval of an Israeli annexation of several West Bank settlement blocs in a final peace deal. Israeli officials, including the foreign minister, have said Washington is unwilling to give such guarantees.

Earlier this week, Israeli envoys met U.S. officials, including National Security Adviser Condoleezza Rice. The officials proposed to evacuate nearly all Gaza settlements, as well as six West Bank settlements, a senior Israeli government official said.

Sharon has suggested the Gaza pullout as part of a plan to reduce friction with the Palestinians in the absence of a peace agreement. The plan is expected to include a limited pullback from the West Bank, where Israel would impose a boundary.