Israel attacked Yasser Arafat's Gaza office by air and sea, killing four guards early Wednesday, a day after violence by both sides left 15 dead in one of the bloodiest periods of the Palestinian uprising.

In a separate raid early Wednesday, Israeli tanks shelled two Palestinian police outposts in the West Bank town of Nablus, killing five policemen, Palestinians said. The Israeli military said only that there was military activity in the area.

As Israeli warships fired machine guns and a missile at Arafat's office, killing the guards, Israeli helicopters sent missiles into nearby police compounds and a warplane dropped a bomb.

The attacks in Gaza, which began at 3 a.m., were still in progress three hours later, witnesses said, adding there were at least 40 explosions.

It was the first time that the Israeli military targeted Arafat's headquarters in Gaza. Arafat was at his West Bank headquarters, trapped there by Israeli tanks.

Palestinians in nearby buildings fled in panic. "This is another night of terror," said Ilham Johfur, who was fleeing with her two small children in tow. They joined hundreds in the streets, fearing their buildings would be hit. About 65 people went to hospitals suffering from shock, doctors said.

The latest Israeli strikes capped one of the most violent days in the 17-month Israeli-Palestinian conflict.

Palestinian gunmen late Tuesday infiltrated an army post near Ein Arik on the West Bank, killing six Israeli soldiers, the Israeli army said. The Al Aqsa Brigades, linked to Arafat's Fatah, claimed responsibility.

Earlier Israeli airstrikes along with shelling and a raid by undercover forces left eight Palestinians dead, including a 14-year-old girl, in the West Bank and Gaza, according to Palestinian sources.

Tuesday began with a Palestinian suicide bomber blowing himself up seconds after he was pushed off an Israeli bus by its suspicious driver near the northern West Bank settlement of Mehola, police said.

The carnage since early Tuesday left 24 dead: the four guards, five policemen, the suicide bomber, eight other Palestinians, and the six Israelis. Palestinian sources said 33 Palestinians were wounded.

The upsurge in violence increased the pressure on Prime Minister Ariel Sharon to take more decisive action.

Deputy Internal Security Minister Gideon Ezra said the Palestinians had taken over the element of surprise, once an Israeli prerogative.

"They attack and we defend. In the past we attacked and they defended," Ezra said. "We need to return to that...we have to control the situation."

A group of 1,200 retired Israeli security officials proposed an immediate Israeli withdrawal from much of the West Bank and Gaza Strip, and the dismantling of 40 to 50 isolated Jewish settlements.

In a position paper published this week, the Council for Peace and Security said troops being used to defend the settlements should be deployed along a line close to the frontier between Israel and the West Bank.

In recent weeks, more than 200 Israeli reserve soldiers have declared they will no longer serve in the West Bank and Gaza Strip.

Sharon decided after consultations with top security officials late Monday to intensify military strikes but stop short of a large-scale military operation. "There will be no strategic change, but there will be wider use of military means," said Sharon adviser Raanan Gissin.

In 17 months of fighting, Israel has launched air strikes against Palestinian Authority installations, raided Palestinian areas, killed suspected militants in targeted attacks and destroyed hundreds of acres of crops.

With 15 Israelis killed over six days, Sharon came under growing criticism by hard-liners in his coalition.

"He doesn't have the right to be prime minister when a Jew is killed every hour," right-wing member of parliament Zvi Hendel told the Yediot Ahronot daily.

Newspaper commentators said Sharon's policy had failed. "The army should either conquer the Palestinian territories, withdraw unilaterally or pursue a peace agreement," Yoav LImor wrote in the Maariv daily.

Arafat said Tuesday that despite the Israeli reprisals, "we are still committed to the peace process." Israel accuses Arafat of professing commitment to peace talks while quietly encouraging militants to carry out attacks.

In Washington, the State Department repeated a call for Arafat to clamp down on Palestinian militants.

"We are deeply troubled by the continuing violence," State Department spokesman Richard Boucher said. "We've made very clear that Chairman Arafat and the Palestinian Authority must take strong, resolute and irreversible action now to halt violence and terror."

In Amman, Jordan, King Abdullah II said that solving the Arab-Israeli conflict can only be achieved through dialogue, not violence. "The policy of violence will only bring more tension and instability to the Middle East," Abdullah said.

His comment came during a meeting with Richard N. Haass, the head of the U.S. State Department's policy planning office, Jordan's official Petra news agency reported.

Tuesday's events were the latest in a string of incidents which began Monday, with three separate attacks.

On the outskirts of Jerusalem Monday, a Palestinian blew himself up, killing himself and an Israeli Arab police officer. A Palestinian gunmen fired at Israelis in the Gaza Strip, killing a civilian and two soldiers before being shot dead. Another Palestinian was killed by Israeli troops as he attempted to carry out a shooting attack.

Near the site where the motorist and the two soldiers were killed, Israeli troops demolished a Palestinian home and severely damaged another on Tuesday.