KAREM SHALOM, Israel - The Israeli soldiers at the makeshift observation post by the Gaza Strip border fence were usually more concerned with catching smugglers than with being attacked by Palestinian terrorists.
This seemed a relatively quiet assignment - free of gunfire and next to a farming cooperative whose residents fed and housed soldiers coming off their shifts.
But in a surprise pre-dawn attack early yesterday carried out under cover of fog and rain, Palestinian gunmen dressed in police uniforms cut through a 15-foot- high fence, climbed a small hill to the post called "Africa" and opened fire with machine guns.
In the end, four Israeli soldiers from the Bedouin Desert Brigade and the two gunmen were dead, a cease-fire that had lasted the better part of three weeks was over and a new round of violence threatened to escalate.
"All the declarations of a cease-fire by the Palestinians mean nothing," said Lt. Col. Olivier Rafowicz, an Israeli army spokesman. "There is no cease-fire. There is only fire."
The Islamic militant group Hamas claimed responsibility for the attack, saying it was carried out in retaliation for Israel's capture last week of a ship loaded with weapons allegedly destined for the Palestinian Authority.
The raid broke the group's pledge to end attacks in Israel. In justifying the raid, Hamas said yesterday that the cease-fire had achieved nothing.
Violence had dropped significantly over the past three weeks, to one or two shooting incidents a day, with no Israeli casualties. Palestinian officials had said it was time to restart negotiations and complained that Israeli leaders' hesitance proved they were not interested in peace.
Pressure to resume talks had also been building in Israel's government, despite resistance from Prime Minister Ariel Sharon, who characterized the respite from violence as a mirage. Yesterday's killings show that if Sharon is reluctant to resume peace talks, he gets plenty of help from uncompromising dissident groups among the Palestinians.
In a common refrain, each side accused the other of thwarting peace. Israeli officials blamed Palestinian leader Yasser Arafat for failing to dismantle militant groups, and Arafat criticized Israel for provoking violence.
Israel's Security Cabinet met yesterday, and sources said a military response was expected today. That could upend efforts by U.S. mediator Anthony C. Zinni, who left the area last week hoping for a quick return to negotiations.
White House spokesman Ari Fleischer called the attack "particularly disturbing, because it came at a time when the situation on the ground had been relatively quiet and the United States has been working intensely ... to help the parties achieve a durable peace."
Yesterday's attack employed a recent tactic in which Palestinian gunmen infiltrate Jewish settlements or army camps and shoot until they themselves are killed. Two similar operations have been carried out in the Gaza Strip in the past few months.
But the small post just outside Kibbutz Karem Shalom, near where Egypt, the Gaza Strip and Israel meet, was an unexpected place for a raid. There are no nearby settlements, and the post is merely a stopping point for roving patrols and is not regularly staffed.
It consists of an olive-green tarp thrown over four poles atop a mound of dirt, protected only by two small stacks of sandbags.
Soldiers who patrol the area are Bedouins, who are not required to serve in Israel's armed forces. About 2,000 Bedouin volunteers serve in combat units.
The Desert Brigade was established 12 years ago and operates along the Gaza Strip border with Egypt, a volatile flash point in the Israeli-Palestinian conflict. Bedouins have been the target of numerous Palestinian attacks, but until yesterday, only three had been killed in combat in the past 15 months.
The four soldiers killed yesterday were three infantrymen in their early to mid-20s and a 28-year-old captain. Two others were wounded, one critically.
Israeli Lt. Itamer Gelbfish said the attack occurred about 4:10 a.m. when up to eight Palestinians cut a hole through the fence. Two approached the army post, apparently undetected.
One gunman climbed the hill and fired into the tent, killing a soldier inside and spattering blood on the interior. Other gunmen opened fire from a sandy embankment at a Humvee, killing one soldier and wounding another.
The captain, hearing the shots, raced up in a Jeep and was killed, along with the soldier who sat by his side. Other soldiers arrived and killed the two Palestinians in what was described as a prolonged gunfight.
Gelbfish said the most trouble at the post usually involves dealing with Palestinians trying to smuggle stolen goods across the fence, or illegal workers trying to reach jobs in Israel. The soldiers are armed and have night-vision binoculars, but not the metal gun turrets and armored vehicles used in other spots that come under more frequent fire.
"This is a quiet area," Gelbfish said, standing next to the tent, from which one can see Israeli farmland spreading to the west, the Gaza Strip to the east and the Egyptian border less than a mile to the south.
The army post was established to guard against border incursions and to protect the kibbutz. The farming cooperative was started in 1969, abandoned in 1995 and re-established just five months ago.
Its manager, Ilan Regev, persuaded about 40 adults to plant peanuts, potatoes and carrots, and to raise turkeys, despite searing summers and the closeness to the Gaza Strip.
"No one thought there could be a danger here," said Regev, 47, noting that the isolated kibbutz of small metal homes and poultry shacks did not seem a particularly inviting target. "We're at the end of the Earth down here."