Israeli planes, helicopters and warships pounded Gaza and the West Bank Wednesday and renewed attacks in the early hours Thursday, carrying out one of its fiercest assaults during the 17-month Palestinian uprising.

Israel moved into the West Bank town of Tulkarem from three directions before dawn and killed one Palestinian, witnesses said. The Israelis declared a curfew and confined people to their homes as helicopters fired missiles, residents said.

The military said soldiers took control of a refugee camp and parts of the town and were carrying out house-to-house searches for terrorist suspects.

Israeli gunboats also fired on Gaza for the second straight day, hitting a Palestinian police roadblock and wounding 13 policemen, three critically, Palestinian security officials and doctors said. Other gunboats fired at Arafat's seaside Gaza office, witnesses said.

The Israeli military said its forces attacked "terrorist targets" including a police post.

Israeli warplanes targeted Palestinian headquarters in Bethlehem with at least two missiles before daybreak, witnesses said. No casualties were reported.

The fighting since Wednesday killed 14 Palestinians and two Israeli soldiers. One of the Palestinian dead included a Hamas activist killed in an explosion at his Gaza City home. Israeli forces also killed a leader of the militant Islamic Jihad, Mohammed Anani, 27, in the village of Siris in the northern West Bank, Palestinians said.

In Washington Wednesday, Secretary of State Colin Powell criticized the heavy retaliation, and said both sides' policies were fueling violence that made peace efforts impossible. "(Prime Minister Ariel) Sharon has to take a hard look at his policies and see if they can work," Powell said. "I don't think declaring war on Palestinians will work."

Late Wednesday, an Israeli helicopter fired a missile at Yasser Arafat's headquarters in the West Bank town of Ramallah, where the Palestinian leader has been trapped for three months by Israeli forces. The missile exploded 50 feet from Arafat's office as he was meeting with a European Union envoy. No one was hurt, officials said.

The Israeli military said the strike on Arafat's compound was "part of Israel's fight against terror."

Amid the worst spate of violence since the start of the conflict 17 months ago, Sharon promised Israel would strike "without letup" until Palestinian militants' attacks on Israelis are reined in.

"This is a really tough war we are in," the Israeli leader told troops and Israeli officials at a military checkpoint south of Jerusalem.

Sharon's foreign minister, Shimon Peres, however, said force was not the answer. "A cease-fire cannot be achieved just by using fire," he told journalists in Jerusalem.

A spokesman for another Cabinet minister, Avigdor Lieberman, confirmed a sardonic closed-door exchange during which Peres told Lieberman that excessively harsh measures against the Palestinians could lead to war-crimes accusations.

U.N. Secretary-General Kofi Annan issued an urgent appeal to both sides to end the violence.

"History will judge them harshly, and their people will not absolve them, if they fail to do so," Annan said, in one of his strongest statements directed at Sharon and Arafat.

In an offensive that began late Tuesday and continued into Thursday in Gaza, Israel fired on targets from the land, sea and air.

After nightfall, Israeli helicopters fired at least six missiles at two Palestinian security buildings in Rafah in the southern Gaza Strip, seriously damaging the structures and others nearby, Palestinians said. One person was injured. The Israeli military said the air strike was "part of Israel's ongoing fight against terror."

Arafat's home in Gaza City and a U.N.-run school for the blind were badly damaged by shrapnel from an air strike Tuesday night on a nearby security compound.

No one was in Arafat's home at the time; he was in Ramallah and his wife and daughter live abroad. At the school, rubble crunched underfoot as young students visited the site Wednesday, accompanied by U.N. officials.

The death of Hamas activist, Abdel Rahman Ghadal, was announced over mosque loudspeakers near his Gaza City home, and the announcement blamed an Israeli missile strike — a claim that could not be confirmed. Israel has carried out dozens of targeted killings of those believed to have orchestrated attacks against Israelis.

Also, soldiers shot and killed two Palestinians who were trying to plant a bomb near a crossing point between Gaza and Israel, military sources said.

In clashes, two Israeli soldiers were killed by Palestinian fire, the military said. The heaviest fighting was reported in the villages of Abassan and Karrara in southern Gaza, where witnesses said 12 tanks moved into the area, drawing intense Palestinian fire. Helicopter gunships fired machine guns toward the gunmen, sending civilians scrambling for cover.

A 40-year-old Palestinian woman was killed by a shot in the back, and two other civilians were critically wounded, Palestinian doctors said. Israeli troops barred ambulances from reaching the two wounded men, who died after being left untreated for about three hours, the doctors said. There was no comment by the army.

Israeli navy gunboats fired at a Palestinian base on the coast north of Gaza City, killing four members of the Palestinian naval police. One officer died after a shell hit his jeep, and the bodies of three of his colleagues were discovered later Wednesday in the rubble of the base.

In the West Bank, Palestinian officials said two Palestinians died at Israeli military checkpoints in separate incidents. The army said one of them was trying to bring in explosives.

Since violence erupted in September 2000, 1,068 people have died on the Palestinian side and 319 on the Israeli side.

The Israeli strike against Gaza came several hours after Palestinians fired two unguided Qassam rockets late Tuesday, hitting the nearby Israeli town of Sderot in a strike that wounded a baby and slightly injured another child.

After daybreak, Israeli F-16 warplanes flattened a two-story office building used by the Palestinian police chief in Gaza, Brig. Gen. Abdel Razek Majaidie. Tanks also moved toward the northern Gaza towns of Beit Hanoun and Beit Lahiya, digging up the main road and building barriers.

The violence has fueled debate inside Sharon's government over whether any political resolution can be found.

Citing the "terrible, terrible" recent days, Peres said Israel should demand from Arafat a clear-cut declaration that he would halt terror, but also have its own army do everything possible "not to escalate the situation."

Peres' bitter exchange with the infrastructure minister, Lieberman, was reported in the Yediot Ahronot newspaper and confirmed Wednesday by Lieberman's spokesman, Sagiv Rotenberg. According to the Yediot account, Lieberman urged that Palestinians be told to halt all terror activity or face wide-ranging attacks.

"At 8 a.m. we'll bomb all the commercial centers ... at noon we'll bomb their gas stations ... at 2 we'll bomb their banks," Lieberman reportedly told the meeting before Peres interrupted to say: "And at 6 p.m., you'll receive an invitation to the international tribunal in The Hague."