GAZA CITY, Gaza Strip – Palestinian Arab terrorists set off a large truck bomb as gunmen stormed an Israeli base at a vital Gaza crossing yesterday, killing five Israelis and three Palestinian Arabs in an attack that defied peace efforts by new Palestinian Arab leader Mahmoud Abbas.

The attack, which hospital officials said wounded five Israelis, was by far the largest since Mr. Abbas won an election Sunday to succeed Yasser Arafat as head of the Palestinian Authority. Mr. Abbas has been trying to persuade terrorist groups like Hamas and Islamic Jihad to agree to a cease-fire, but so far with no success.

The bombing also came just hours after a West Bank Hamas leader said the Islamic group might consider an end to attacks against Israel. Hamas was one of three terrorist groups claiming responsibility for the attack, dubbing it “Shaking Castles.”

Palestinian Arab officials were not immediately available for comment.

The attack took place just before 11 p.m. Gaza time at the Karni crossing, where all farm produce and other goods enter and leave the Gaza Strip. The terrorists entered the crossing in a bomb-laden truck minutes before it was to close, the Israeli military said. As the explosives detonated, at least two gunmen stormed the Israeli positions.

It was not immediately clear whether the bombing was a suicide attack. One report said the gunmen blew themselves up, but another said they opened fire and were killed by Israeli soldiers.

Early Friday, Israeli helicopters fired three missiles at a building in Deir el-Balah in central Gaza, Palestinian security officials and the Israeli military said. The building, which was empty, is used by Islamic Jihad, they said. One person was slightly wounded.

Israel intends to pull out of Gaza in the summer. Terrorist groups have been stepping up their attacks in recent months in an attempt to show that they are forcing the Israelis out. A month ago, soldiers discovered a tunnel terrorists were digging toward the Karni checkpoint in an attempt to blow it up.

An Israeli rescue worker at the scene, Yehuda Shoshan, said five people were killed in yesterday’s attack. “So far we have identified four Israeli [dead]. The fifth has not been identified,” he told Israel Radio. Hospital officials said they were treating three seriously wounded people and two slightly wounded.

A statement from the Al Aqsa Martyrs Brigade, affiliated with Mr. Abbas’s Fatah faction, said two fighters were killed “in a martyrdom operation” near the Karni crossing. Later, a terrorist faction said a third gunman was killed while trying to ambush rescue workers.

A spokesman for another group, the Popular Resistance Committees, said terrorists filmed the attack. Hamas also claimed responsibility in the joint operation.

Just hours earlier, the top Hamas official in the West Bank, Sheik Hassan Yousef, said that Hamas is open to a truce with Israel and is no longer bent on destroying the Jewish state, recognizing that Palestinian Arabs are weary after four years of conflict.

The comments went a step beyond previous Hamas statements indicating it might accept Israel as a temporary presence only.

Yousef, who is among Hamas’s founding members, is known as a relative moderate within the group, and other leaders couldn’t immediately be reached for reaction. The group’s main leaders are based in Syria and Lebanon, and they usually stick to the Islamic terror movement’s uncompromising line against Israel.

Yousef said the group is reconsidering its violent tactics, though a final decision hasn’t been made.

The official ideology of Hamas does not recognize a place for a Jewish state in an Islamic Middle East. In the past, the furthest Hamas leaders have gone is to say they would accept a “temporary” Palestinian Arab state in only the West Bank and Gaza Strip in the framework of a long-term cease-fire with Israel – but that Hamas would not make peace with the Jewish state and believes the Palestinian Arabs have the right to all Israeli land.

Yousef said Hamas understands that the Palestinian Arab people are weary after more than four years of fighting. “We read the regional and the international reality and the changes that have taken place based on this reality, and we take positions according to these changes,” Yousef said.

“Hamas doesn’t want to eliminate Israel. Hamas is a realistic political movement,” he said. “There is a thing called Jews and a thing called Israel and we deal with this reality.”

Despite Yousef’s comments yesterday, Israelis were skeptical.

“We’re going to have to see what the reaction is. This guy has a reputation for piping off,” cautioned an analyst at the Jaffe Center for Strategic Studies at Tel Aviv University, Mark Heller. “I don’t think he was speaking for the movement.”

A senior Israeli official, speaking on condition of anonymity, said Israel would deal only with Mr. Abbas’s Palestinian Authority.

Israel insists that Mr. Abbas dismantle the terrorist groups, according to the terms of the stillborn “road map” peace plan, backed by America, United Nations, European Union, and Russia.