Associated Press Mourners gather around the bodies of six Palestinians killed during an Israeli incursion into a Rafah refugee camp in southern Gaza Strip yesterday. After losing 13 soldiers in the past week, Israel is changing its military tactics to deal with what it views as a guerrilla war.

JERUSALEM - Taking a step to ease tensions, Palestinians said yesterday they had arrested three suspects in the assassination of an Israeli Cabinet minister, yet the Israelis kept up punishing raids, and Palestinian militants carried out more attacks.

Israel said the three must be put on trial before the blockade on Palestinian leader Yasser Arafat's office in the West Bank town of Ramallah is lifted. Arafat said the men would be brought before a Palestinian court.

Israeli airstrikes hit Arafat's Ramallah office and other targets in the third day of reprisals after deadly Palestinian attacks. Four Palestinian civilians, three gunmen and an Israeli Arab were killed in Israeli raids and clashes yesterday. The attacks continued after nightfall, with Israeli helicopters firing missiles at buildings in Gaza City, witnesses said.

Speaking to reporters, Arafat repeated his call to stop the fighting, referring to "the initiative that I began on Dec. 16 to make the cease-fire hold," the date of a televised speech Arafat made shortly after Israel began its siege.

Prime Minister Ariel Sharon was due to make a televised address yesterday - a relatively rare event in Israel - amid conflicting demands among Israelis for a dramatic shift in policy after a sudden upsurge in violence.

Hard-liners insist on a stern military response, including expulsion of Arafat, while doves say military victory is impossible, and Israel should restart negotiations with the Palestinians while considering unilateral pullout from parts of the West Bank and Gaza.

A Palestinian gunman opened fire on a military checkpoint, wounding two soldiers, in an attack reminiscent of one Tuesday in which six Israeli soldiers were killed.

Soldiers returned fire in yesterday's assault, killing the Palestinian and an Israeli Arab who drove him to the site. Israeli officials said the Israeli Arab was unaware that the Palestinian was a gunman.

Early yesterday, Israeli forces entered Gaza City for the first time, destroying a four-story building housing a broadcasting station. Residents all over the city could see the hilltop antenna tower crash to the ground.

At the same time, Israeli tanks entered the southern Gaza city of Rafah. Five Palestinians were killed by Israeli gunfire.

Palestinians said Israeli forces took over four apartment buildings in Nablus, near the Balata refugee camp, home of the leader of a militia affiliated with Arafat's Fatah faction that claimed responsibility for the Tuesday checkpoint assault.

Palestinians said Israeli soldiers abused and humiliated the residents of the building. The Israeli military denied the charges.

The Palestinian attacks at checkpoints and gunfire along West Bank and Gaza roads, aimed at Israeli soldiers and settlers, were evidence of a change in tactics after nearly 17 months of violence.

Palestinians close to militant groups said operations in the territories the Palestinians claim as their own could win them world sympathy, while grisly suicide bombing attacks inside Israel drew withering criticism.

Israeli officials acknowledged the change in targets and tactics, saying that they were facing a guerrilla war instead of random terrorism and would respond with small commando operations aimed at militants.

However, there was no sign of a change yesterday. Israeli air strikes against Palestinian security buildings in the West Bank and Gaza continued until midday. One helicopter-borne missile blasted a hole in the wall of a building in Arafat's Ramallah compound, the closest the Israelis have come to hitting the Palestinian leader.

Arafat walked down a darkened hallway to inspect the damage. Helped by two aides to navigate through the rubble of the lounge where he receives foreign diplomats, he said, "tanks and aircraft cannot frighten the Palestinian people or their leadership."

Even so, Palestinian security took a large step toward easing tensions by arresting three suspects in the Oct. 17 assassination of Israeli Cabinet minister Rehavam Zeevi, fulfilling a key Israeli condition for lifting the three-month tank siege that has trapped Arafat in Ramallah.

But Raanan Gissin, Sharon's spokesman, said Israel would lift the blockade only if the three are put on trial. Benny Elon, a hard-line Israeli Cabinet minister, demanded instead that the suspects be extradited to Israel for trial.

Arafat said they would be "put on trial in our territories," and said Israel had no right to demand their extradition. Interim peace accords include the possibility of extradition of Palestinian suspects if they are not put on trial in Palestinian courts.

Palestinian security agents broke into an apartment in Nablus where the three were hiding and detained them, said the Palestinian intelligence chief in Nablus, Col. Talal Dweikat. He said the arrest order came directly from Arafat.

The three are leading members of the Popular Front for the Liberation of Palestine, which claimed responsibility for the assassination, calling it retribution for Israel's killing of PFLP leader Abu Ali Mustafa last August.

The PFLP is the second-largest component of Arafat's PLO. PFLP leader Ahmed Saadat was detained several weeks ago and is being held at Arafat's Ramallah headquarters, Palestinians say.