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This northern Arab town on Friday buried four townspeople gunned down by a Jewish soldier opposed to Israel's impending pullout from the Gaza Strip (search).

Mourners heaped flowers and lit candles on a makeshift altar fashioned from window frames ripped from the bus where 19-year-old Eden Natan-Zada (search) opened fire Thursday, killing the driver and three passengers and wounding more than 20.

An enraged mob beat Natan-Zada to death and prevented police from removing his body from the bus for hours.

Thousands of police fanned out across northern Israel (search) and Jerusalem on Friday to guard against rioting. Hamas militants in Gaza ratcheted up the potential for violence by threatening retaliation for the attack.

Natan-Zada's body was being held at a morgue after the military, his hometown of Rishon Lezion and the extremist settlement where he recently moved refused to bury him.

For months, Israeli security has been warning that extremists might try to sabotage the mid-August pullout from Gaza and four small northern West Bank settlements by attacking Arabs and diverting security forces.

Natan-Zada's father said that his son deserted his army unit after he was ordered to help prepare for the pullout and that he moved to the West Bank settlement of Tapuah.

In Shfaram, thousands of Muslims, Christians and a small group of Jews turned out for a quiet funeral procession from the home of two sisters killed in the attack to the cemetery where they were buried.

Dozens of women in the march chanted mournfully, "Some day we hope to die this way as martyrs, as martyrs," and flashed victory signs.

Townspeople lit hundreds of candles and placed hundreds of flowers on the impromptu altar at the site of the attack. Melted candle wax seeped onto high-heeled shoes, flip-flops, door handles, seat frames and other objects taken from the bus where the victims met their death.

A fire burning in a small drum stood at the head of the altar. Behind it, children and adults held up banners in Hebrew and Arabic reading, "We are fed up with racism," "Search me, I'm an Arab" and "Bring those who allow racism to justice."

At a protest against the killings in Gaza City, Hamas leader Nizar Rayan served notice to "wait for our response."

Wearing the skullcap, beard and sidelocks of an ultra-Orthodox Jew, Natan-Zada boarded a bus bound for Shfaram, a city of 35,000 Muslims, Christians and Druze.

When the bus entered a Shfaram neighborhood, he fired at the driver, killing him instantly, witnesses said. The bus rolled on for 50 yards, until it hit a parked car and stopped in front of a grocery store. Natan-Zada continued shooting inside the bus, emptying a magazine. When he tried reloading, he was tackled and disarmed.

Husam Elian, a former soldier from Shfaram who was driving in a car directly behind the bus, was one of several people who helped stop the attack.

"I was driving when I heard rapid gunfire," Elian said. "I pulled out my gun, because I am a security guard, and went toward the bus. Someone told me there was a man, an Israeli soldier, with a gun, and then I saw him, and he started shooting at me and my neighbors. I saw some friends, and they ran with me onto the bus. And just as he was changing magazines, that's when we grabbed him."

Elian said his friend shouted at Natan-Zada, "Do you know Israeli soldiers could be on this bus?" Natan-Zada replied, "There are Arabs on this bus."

Elian said he and his friends tried to shield Natan-Zada, but there weren't enough police officers to keep hordes from boarding the bus.

"Getting him out was impossible," Elian said.

The gunman's body lay on the bus floor, his head covered with a black plastic bag, for hours Thursday night until the crowd was subdued. His shirtless upper torso was heavily bruised and bloodied.

The windows of the bus were shattered by bullets and by rocks the mob threw at him. Blood stained bus seats, and rocks covered the vehicle's floor.

Three juveniles from Tapuah, ages 15 to 17, were arrested in connection with the shooting, Channel 2 TV reported. The settlement is dominated by followers of U.S.-born Rabbi Meir Kahane, who advocated expelling Arabs from Israel and the West Bank. Kahane was assassinated in New York in 1990.

Israel's military chief, Lt. Gen. Dan Halutz, said he was "definitely worried that people on the fringes are going too far."

Prime Minister Ariel Sharon issued a statement condemning the attack as "a despicable act by a bloodthirsty terrorist."

It was the bloodiest such incident in Israel since 1990, when an Israeli opened fire at a bus stop where Palestinians gathered for job placements, killing seven.

In 1994, Baruch Goldstein, an American-born Jewish settler, entered a holy site in the West Bank city of Hebron and opened fire on Muslim worshippers, killing 29 — the bloodiest attack by a Jewish extremist against Palestinians.

Palestinian leader Mahmoud Abbas called on Israel to prevent Jewish settlers from carrying weapons, "because they are dangerous to the security and peace between the two people." Many Jewish settlers have army-issue guns to protect them from militants.

Israeli Arabs make up about 20 percent of Israel's population of 6.9 million. Though they are full citizens, they have suffered from discrimination by Jewish-dominated governments. Many of their towns and villages lack basic infrastructure, and Arab localities usually top of Israel's unemployment lists.