Hours after a female Palestinian homicide bomber blew herself up Saturday inside a popular seaside restaurant, killing 19 people, Israel retaliated with air strikes in the Gaza Strip (search).

Israeli helicopters swept into Gaza City early Sunday and fired missiles at an empty home near the beach, witnesses said. The home, which had been empty for some time, belonged to a family with members in Palestinian militant groups.

In a Palestinian refugee camp in central Gaza, helicopters also fired on a house belonging to a leader from the Islamic Jihad (search) militant group, which took responsibility for the homicide attack, witnesses said.

The Israeli military said it was seeking to destroy arms caches stockpiled by Hamas. There were no reports of casualties in either strike.

The lunchtime homicide attack came on the day before Yom Kippur (search), the holiest day of the Jewish calendar that commences at sundown on Sunday. One of the deadliest bombings in three years of violence, the blast ended nearly a month of relative calm. Four children were among the dead and at least 55 people were wounded.

The homicide bombing fueled speculation that Israel might act on threats to "remove" Palestinian leader Yasser Arafat (search). Israeli Prime Minister Ariel Sharon (search) holds Arafat responsible for homicide attacks, even those carried out by Islamic militant groups opposed to the Palestinian leader's rule.

President Bush called the attack “despicable” and said Palestinian authorities must take responsibility for stopping terrorism. Arafat supporters appealed for international intervention to guarantee his safety.

Sharon called his advisers for an emergency meeting Saturday evening, and the helicopter attacks happened shortly after.

"The world will have to accept our decisions," Ehud Olmert, Israel's vice premier said before the meeting.

The Gaza house targeted by the helicopters belonged to the Kanita family, one of Gaza's largest, but had been empty for a long time. The Kanita family has members in all the main Palestinian groups, including the violent Hamas and Islamic Jihad, Palestinians said.

The attack at the Boureij refugee camp targeted the home of Islamic Jihad leader Morshet Shahin (search), but residents said he escaped.

The blast at the Maxim restaurant went off shortly after 2 p.m., shattering windows and leaving the white walls cracked and charred black. Most of the ceiling had collapsed, with lights and wires dangling.

Broken plates, glass, chairs and human remains covered the floor of the one-story building. Outside, the body of the restaurant's security guard lay broken and bloody on the steps.

Police said the bomber and 19 bystanders were killed. A 1-year-old and two other children, ages five and six, were among the dead, emergency officials said.

Also among the dead were four Arabs, and the wounded included several members of the local pro soccer team, Maccabi Haifa, who meet at the restaurant every Saturday.

ZAKA, a group that aids rescue workers and gathers body parts for burial, said that five members of one family and three from another died.

Gideon Zilberstein, a 63-year-old accountant, was eating lunch with his wife, son and daughter-in-law when the bomber attacked. "Suddenly we heard a huge boom all around us. People were dead or dying next to our table," he said.

Haifa, a Mediterranean port city of about 270,000 with a reputation for tolerance, has been the target of repeated attacks by militant groups -- perhaps because attackers are better able to blend in here with the Arab community of 47,000.

Despite a Sept. 11 Cabinet decision to "remove" Arafat at some point, Israel might shy from carrying out the threat because of strong U.S. opposition and concerns about an international backlash.

Instead, Israel could settle for a lesser step, such as increasing Arafat's isolation by installing more tanks and troops around his West Bank headquarters, where he has been confined for nearly two years. The helicopter attacks may have been just such a step.

An Israeli Foreign Ministry official said the next two days would be crucial for the survival of a U.S.-backed peace plan, suggesting Israel might not take any immediate drastic action.

U.S. Secretary of State Colin Powell called Israeli Foreign Minister Silvan Shalom on Saturday to discuss the situation. Earlier, Shalom had reassured Powell that Israel would consult with the Washington before acting against the Palestinian leader.

Israeli Foreign Ministry spokesman Jonathan Peled said Israel expected Arafat to take swift action against the militants. The Palestinian leader "will have to come up with something very, very different or serious this time to get off the hook," Peled said, adding that "the next 24 to 48 hours are crucial for the future of the ... peace process."

Arafat condemned the homicide attack, saying it would harm the Palestinian cause. Incoming Palestinian Prime Minister Ahmed Qureia expressed his condolences in a phone call to the Haifa mayor.

Eight Israelis joined 18 members of the pro-Palestinian International Solidarity Movement (search) at Arafat's battered headquarters, pledging to act as a human shield to prevent Israeli action. The ISM activists hailed from the United States, Canada and four other countries.

The United States is looking to the new Palestinian prime minister to crack down on militants; the bombing came on the eve of the expected announcement of a new cabinet by Qureia, who was an architect of the 1993 Oslo peace agreements.

The Islamic Jihad group said it organized the bombing, identifying the assailant as Hanadi Jaradat, a 27-year-old law school graduate from the West Bank town of Jenin. Her brother and a cousin, an Islamic Jihad member, were killed in an Israeli military raid in June.

British Prime Minister Tony Blair also condemned the attack -- the first homicide bombing since twin attacks killed 15 people on Sept. 9, near an army base outside Tel Aviv and at a Jerusalem coffee shop.

Those attacks prompted the Israeli security Cabinet to vote to "remove" Arafat, a threat interpreted as either expelling or killing the Palestinian leader.

Sharon had hinted Israel might act against Arafat in response to an attack with many casualties. The United States opposes expelling Arafat, and Israel's security chiefs are divided on the issue. Sharon and Defense Minister Shaul Mofaz, who has spoken in favor of expulsion, have the final say and need no Cabinet approval.

Israeli Health Minister Dan Naveh said Israel must not hesitate. "This awful attack today is definitely an opportunity, the correct opportunity, to implement the Cabinet decision to get rid of Arafat," he said. "It is clear to all of us that he is the biggest obstacle to reaching better days."

Chief Palestinian negotiator Saeb Erekat appealed to international mediators to intercede on behalf of the Palestinian leader, saying he is "worried about an Israeli action against President Arafat or against the Palestinian people that may just add to the complexities."

There were conflicting reports about how the attack began, with some saying the bomber shot the security guard at the entrance before rushing into the restaurant.

If true, that would represent a new tactic. In the past, security guards stopped several bombers outside restaurants, cafes and shopping malls. Police Commissioner Shlomo Aharonishki said it was not clear whether shots were fired.

Saturday's bombing brought to 103 the number of homicide bombings in the past three years of Israeli-Palestinian fighting. At least 431 people have been killed in these attacks.

The attack came despite a blanket closure Israel had imposed Friday on the West Bank and Gaza Strip ahead of Yom Kippur, which begins at sundown Sunday and ends at sundown Monday. Such closures are generally imposed during Jewish holidays because of increased concerns about attacks.

The Associated Press Contributed to this report.