Israel (search) lowered a road barrier sealing the Gaza Strip (search) to Israeli civilians at midnight Sunday — signaling the start of a historic withdrawal that will end its 38-year occupation, redraw borders and reshape prospects for Mideast peace (search).

But several hundred settlers vowed stay in their homes and ignore orders to leave Gaza within 48 hours. They were reinforced by up to 5,000 hard-line activists from outside Gaza who planned to block forceful evictions.

Trouble surfaced shortly after the ceremony when hundreds of protesters from the largest settlement, Neve Dekalim, blocked the main road, stopping army vehicles and scuffling with soldiers.

At the border, soldiers lowered a red road barrier at the Kissufim Crossing between Israel and Gaza, with a sign on the barrier reading: "Stop, entry into the Gaza Strip and presence there is prohibited by law."

With about 200 people looking on, the barrier was raised and lowered several times, apparently because of technical problems. Soldiers secured it with a wire to keep it shut.

Two large Israeli flags waved beside the barrier. As it went down, a traffic light changed from green to red and three vans carrying settlers and their belongings drove out of Gaza, never to return.

"The Gaza Strip has been closed today based on the decision of the Israeli government and today another phase begins," said Brig. Gen. Guy Tsur, a senior commander.

The withdrawal, marking the first time Israel gives up settled land claimed by the Palestinians for their future state, comes after months of political wrangling and mass protests. On Sunday, Israeli troops took up positions to launch the evacuation and Palestinian security forces fanned out to prevent militant attacks.

Israel's army chief appealed to troops to show restraint in removing thousands of Jewish settlers from their homes amid concerns that resistance could turn violent after thousands of anti-pullout activists slipped into the territory.

The presence of a few thousand Israelis in Gaza, among 1.3 million Palestinians, has become a security burden, said Vice Premier Ehud Olmert. "The state of Israel does not want to be in the Gaza Strip and does not need to be in the Gaza Strip," he told Israel TV's Channel One.

In the hours leading up to the closure, thousands of Palestinian police moved into positions near Jewish settlements with orders to keep away Palestinian crowds and to prevent attacks by militants during the pullout — something that Israel warned would bring harsh retaliation.

Officers planted Palestinian flags and pitched tents while some chanted in praise of their late leader, Yasser Arafat. Hundreds of supporters of the militant Islamic Jihad group celebrated in Gaza City, with gunmen firing in the air, and teens setting off fire crackers and distributing sweets. The violent Hamas group organized special midnight prayers of thanks at Gaza mosques.

Palestinian residents watched settlers packing up. "They are actually leaving. Who would have ever thought?" said Palestinian farmer Ziyad Satari, 40, standing on the roof of his three-story home in the Palestinian town of Khan Younis, which overlooks the Morag settlement. Many Palestinians have expressed doubt that the withdrawal will take place.

Palestinian Authority leader Mahmoud Abbas offered the Israelis reassurance.

"We tell the Israeli people, `You have chosen the right path,"' he told Israel TV's Channel 10. "This is the right path. Don't listen to the voices of the extremists who want a continuation of the occupation. I don't want — and I will not accept — any clashes with the army or the settlers."

However, there were exchanges of fire early Monday between soldiers and Palestinians near the Kfar Darom settlement, and mortar shells fell in two settlements and near an army base. No casualties were reported.

Early Monday, the military will distribute eviction notices to the settlers, but it called off plans to enter five of the 21 settlements, said army spokeswoman Maj. Sharon Feingold. She said the reason was to "respect the wishes" of the settlers, who preferred to receive the notices by mail. Earlier, settlers there had said they would block the entrances to their villages.

"It is OK to cry with them," the army chief, Lt. Gen. Dan Halutz, told commanders in urging troops to show understanding of the traumatic time for settlers. During the two-day grace period, "we are there to take it and not to dish it out," he added.

However, once forcible removal begins Wednesday morning, soldiers will act with determination, Halutz said.

As part of Prime Minister Ariel Sharon's withdrawal plan, which was approved by parliament, Israel also will evacuate four small settlements in the northern West Bank housing some 500 people.

Many hope the pullout from the territory Israel captured in 1967 will be the start of a true partition of historic Palestine between Arab and Jew.

Others fear it is a ploy by Sharon to get rid of areas he doesn't consider crucial to Israel while consolidating control of parts of the West Bank, where the vast majority of the 240,000 Jewish settlers live.

The Palestinians want to create their own state out of the Gaza Strip and West Bank, with east Jerusalem as their capital.

Halutz estimated Sunday that about 5,000 outsiders had managed to sneak into Gaza in recent weeks despite army restrictions. The hard-line activists pledged to help the several hundred Gaza settlers vowing to ignore the deadline to leave at midnight Tuesday. The protesters planned to try to close off their communities Monday by massing at entrances and blocking roads to prevent soldiers from delivering eviction notices.

But many families packed their belongings and left the Gaza Strip in recent days, and more were leaving Sunday.

In the Peat Sadeh settlement, Yaakov Mazaltareen set fire to his two warehouses that contained irrigation equipment and two vehicles. He used his forklift to knock down what was left of the structures. Settlers stopped to watch. One crying woman rushed her children away.

Most residents of Peat Sadeh already moved to Israel and were spending the weekend in a hotel.

Dozens of anti-pullout protesters put up tents in the beachfront settlement outpost of Shirat Hayam. They turned a dilapidated house into a storeroom, piling up diapers, bottled water and canned foods. Women cooked on open fires, children bathed in makeshift bathrooms and people chatted in open tents.

At a synagogue in Neve Dekalim, Gaza's largest settlement, seven people sat in the sanctuary and quietly prayed. Itai Ben Simchon, 17, came to the synagogue to collect his father's prayer shawl and said his family decided to leave on their own so as not to lose out on compensation money. "My mother and father are crying a lot," he said.

Pinchas Ariel, a farmer from the Ganei Tal settlement, said he also was leaving on his own because he couldn't face clashing with Israeli soldiers. "I was in the army. I have two sons who were paratroopers, and I'm not going to fight my sons," he said.

Earlier Sunday, hundreds of settlers sang traditional prayers of redemption as part of a ceremony at the Gush Katif cemetery to commemorate the Tisha B'Av holy day marking the destruction of the Jewish Temples. The cemetery's 49 graves are to be moved to Israel — one of the most emotionally charged issues in the pullout.

Vice Premier Shimon Peres gave a pep talk to troops near the Gaza border.

"The settlements must be evacuated. They cannot stay here," he told reporters. "I understand that there are feelings. I have sympathy (for the settlers), but they cannot replace a national choice."