JEBALIYA REFUGEE CAMP, Gaza Strip (AP) _ Armored vehicles massed on Gaza's border Friday after Israel's security Cabinet approved a large-scale military operation _ dubbed ``Days of Penitence'' _ to stop Palestinian rocket fire.
Defense Minister Shaul Mofaz had ordered troops to ``exact a price'' from the militants, security officials said, after a Hamas rocket killed two children, ages 2 and 4, in an Israeli border town.
Hundreds of troops, backed by tanks and helicopters, have been operating in northern Gaza since Wednesday, but more soldiers were expected to move into the area in coming hours.
The Cabinet approved the offensive late Thursday, at the end of a day of heavy fighting between troops and Palestinian gunmen in the Jebaliya refugee camp, the Palestinians' largest and most densely populated.
In bloodshed Friday, five Palestinians were killed and 17 wounded in two missile strikes in Jebaliya. The army said troops fired at one group of militants planting explosives and another setting up a rocket launcher.
A sixth Palestinian died of injuries sustained the day before.
On Thursday, 28 Palestinians were killed and 139 wounded, most of them in Jebaliya. It was the highest single-day toll in fighting in 30 months. In violence elsewhere in Gaza that day, two Israeli soldiers and a settler were killed by Palestinian fire.
Prime Minister Ariel Sharon told the security Cabinet he was determined to stop the rocket fire. Israeli officials said the operation would be open-ended.
``What can we do,'' a participant quoted Sharon as saying. ``The Jews, too, have a right to live.''
In addition to the two children, three Israelis were killed in Gaza on Thursday: two soldiers and a woman settler.
However, Justice Minister Yosef Lapid, a member of the security Cabinet, said it would be impossible to stop the crude rockets for good.
``It's such a simple weapon,'' he said. ``It's impossible to ensure there won't be some pipe with explosives hidden in somebody's backyard.''
On Friday morning, some 200 tanks, armored personnel carriers and bulldozers assembled along Israel's border north and east of Gaza. Troops were setting up makeshift camps, apparently in preparation for an extended operation. Some officers were going over maps.
Thursday's battle in Jebaliya pitted hundreds of gunmen with homemade rockets and assault rifles against the mightiest army in the Middle East, at first glance a hugely lopsided fight.
However, in four years of conflict, Israeli troops had never before struck deep inside the camp for fear of getting bogged down in urban combat.
The fight over control of Jebaliya, the birthplace of the first Palestinian uprising in 1987, could take on great symbolic value.
Militants have been stepping up attacks on Israelis in recent months in hopes of portraying Israel's planned withdrawal from Gaza in 2005 as a retreat under fire. The army has been pounding the militants in intensifying strikes to deny them such claims.
Mofaz, the defense minister, said that when Israel withdraws, it will not be under fire.
``The army, together with ... other forces, is making an effort so this reality will not come about,'' he said during a tour of Gaza.
After a relatively quiet night, gunmen were taking up positions in Jebaliya alleys Friday. In one incident, two Hamas militants were killed by an Israeli missile as they tried to fire a homemade Qassam rocket, the army said.
Nizar Rayan, the top Hamas leader in northern Gaza, encouraged the gunmen and gave them tips in a message broadcast in mosques and on a local radio station late Thursday.
Rayan said gunmen should not remain in one place for more than three minutes to avoid being spotted and should use their cell phones only when absolutely necessary. The militants, who were moving in small groups of no more than seven, communicated largely through text messages on cell phones.
Militants immediately followed one of Rayan's tips: reducing visibility by burning tires and filling the air with black smoke, thus making it harder for Israeli unmanned aircraft, or drones, to spot them.
Hospital officials, meanwhile, said all seven Palestinians killed Thursday by an Israeli tank shell were boys between the ages of 13 and 17.
The army said the tank fired the shell at a group of gunmen near Jebaliya's market after they threw explosives at an armored vehicle.
Twenty-three Palestinians were wounded, including many who lost limbs, and at least four of the wounded were younger than 14, doctors said.
Maj. Gen. Dan Harel, the army commander in Gaza, said Thursday that ``we are very sorry that civilians are being hurt,'' but he also accused gunmen of using civilians as a shield.
Capt. Sharon Feingold, an army spokeswoman, said six cells of militants involved in firing rockets have been killed in the current operation.
Palestinian militants have fired hundreds of rockets and mortar shells at Gaza settlements and Israeli border towns since 2000. Most attacks caused damage and minor injuries.
There have been two deadly strikes, including Wednesday's hit on the border town of Sderot that killed two children playing on the sidewalk in a quiet neighborhood at the onset of the Jewish holiday of Sukkot.
Continued rocket fire could turn public opinion against Sharon's plan to withdraw from Gaza. His opponents argue that a withdrawal would only encourage Palestinian militants to stage more attacks.
Israeli government spokesman Gideon Meir said Israel was forced to act after 11 previous operations in northern Gaza failed to stop the rockets.
``No government can tolerate the continuation of ... missiles falling on the heads of the civilian population,'' he said.
Palestinian Cabinet minister Saeb Erekat denounced the Israeli raid as ``a war crime and state terror,'' and said he feared all of Gaza would soon be reoccupied.