SHIRAT HAYAM, Gaza Strip -- Jewish settlers enraged by a clash with Israel troops near this settlement turned on Palestinians, touching off a violent melee that left at least three people wounded, including one Palestinian in critical condition.
Palestinians responded by hurling rocks at the settlers, and soldiers fired in the air to separate the sides, the army said. The settlers then returned to an abandoned Palestinian home where they had been holed up. Troops declared the area a closed military zone and evicted the Jewish squatters at sunset, arresting many, witnesses said.
In Israel, a planned nationwide protest fizzled after thousands of police were out in force to keep highways open. Protesters blocked the entrance to Jerusalem, a highway near Tel Aviv and a Haifa intersection, but the actions were no more than briefly inconvenient to motorists -- falling short of pullout opponents' hopes.
Earlier, demonstrators managed to briefly block the main Jerusalem-Tel Aviv highway when they threw oil and nails on the road.
The violence drew sharp condemnation from Prime Minister Ariel Sharon, who called on authorities to use an "iron fist" against extremists who he said are threatening to divide the country.
Israel plans to withdraw from Gaza and four small West Bank settlements in mid-August, uprooting about 9,000 Jewish settlers from their homes. While mainstream settler groups say they will resist only through civil disobedience, authorities fear some extremists could turn violent.
The clash near the Shirat Hayam settlement erupted shortly after Israeli soldiers tried to remove about 20 young settlers who holed up in an abandoned Palestinian house earlier this week. The settlers set up the outpost after troops demolished 11 nearby buildings that the army said were going to be used as centers of resistance during the Gaza pullout.
Dozens of Jewish youths exchanged blows with soldiers, and troops dragged several youths through the sand into a waiting army vehicle. Police arrested at least eight people, officials said.
Following the incident, settlers moved outside and headed toward the nearby Palestinian area of al-Mawasi. "They were throwing stones, destroying our houses," said Ahmed Laham, a Palestinian resident.
Hospital officials said a Palestinian was critically wounded after being hit in the head by stones. The army said one soldier and one settler were slightly wounded.
Earlier Wednesday, extremist opponents of the pullout scattered nails and oil across the main Jerusalem-Tel Aviv highway, disrupting traffic and damaging several cars.
"When we find out who did this we will deal with them with the full force of the law. This could have caused a terrible accident," Internal Security Minister Gideon Ezra told Israel Radio. "We will act with all the power we have to prevent these road blockings," Ezra said.
An extremist group called "National Home" announced plans to block more than a dozen highways at 5 p.m. Wednesday, during evening rush hour.
The group stopped traffic last month, sending teenagers and children to sit down on roads behind burning tires. Dozens were arrested.
National Home condemned Wednesday morning's protest and said it was not involved.
"This is a dangerous provocation that endangers lives and runs contrary to our principles of nonviolent civil disobedience," the group said. The main Gaza settlers' group also condemned the protest.
Also Wednesday, police said they had arrested a number of opponents of the withdrawal who were planning to disrupt water and electricity supplies.
At a meeting with senior members of his Cabinet, Sharon angrily denounced the mounting violence.
"We cannot allow gangs to undermine the country," Sharon said, according to participants. "We have to act with an iron fist against hooligans."
Sharon also said hard-line rabbis who urge their followers to resist the evacuation should be punished. Many opponents of the withdrawal are Orthodox Jews, who accuse Sharon of giving up land promised to the Jews in the Bible.
Despite the vocal resistance, many settlers are coming to terms with their impending move. A farmer on Wednesday began dismantling his greenhouses in the Gadid settlement, the first member of Gaza's powerful agricultural community to take concrete steps to prepare for the move.
Salim Michaeli said he was folding up his 60 greenhouses while he negotiates with the government over a new place for them inside Israel. Gaza is one of the country's most profitable farming areas, exporting such goods as vegetables and flowers to Europe.
Sharon has also warned the Palestinians against attacking soldiers or settlers during the withdrawal, promising harsh retaliation.