Israel sent helicopters to kill a senior Hamas political leader in the crowded streets of Gaza on Tuesday but failed, leaving two other Palestinians dead and 27 wounded. The missile attack threatened to rekindle a cycle of violence and wreck a new U.S.-backed peace effort.

Wounded Hamas leader Abdel-Aziz al-Rantissi lies in a hospital bed June 10, 2003 in Gaza City, in the Gaza Strip. Al-Rantissi, a political leader of the militant Islamic group Hamas, survived an Israeli missile strike on his car in Gaza City Tuesday.

The strike against Abdel Aziz Rantisi drew a reproach from President Bush, who said he was "deeply troubled" by the violence, and vows of vengeance from the Islamic militant group, which threatened new suicide bombings and attacks on Israeli political leaders.

Hours after the attack on Rantisi, five homemade rockets fired from Gaza landed in Israel, the Israeli army said. Israeli helicopters and tanks responded by firing on an area in northern Gaza, killing three Palestinians, including a 16-year-old girl.

Two other Palestinians were killed Tuesday by Israeli soldiers in southern Gaza.

Palestinian officials angrily accused Israel of sabotaging their attempts to persuade Hamas and other militant groups to stop attacking Israelis. Palestinian Prime Minister Mahmoud Abbas called the strike a "terrorist attack." Still, Egyptian mediators were going ahead with an attempt to secure a Hamas cease-fire.

U.N. Secretary-General Kofi Annan condemned the strike, saying it complicated efforts by Abbas to halt violence.

Annan's spokesman Fred Eckhard said the secretary-general will go to Washington on Wednesday for talks on the peace blueprint with Secretary of State Colin Powell and national security adviser Condoleezza Rice. The talks will also cover Iraq, Eckhard said.

Israeli Prime Minister Ariel Sharon made clear Israel would not restrain its troops from retaliating against militants, despite U.S. efforts to push forward the peace plan, inaugurated by Bush, Sharon and Abbas last week.

Israel will "continue to fight the heads of the extremist terrorist organizations - those who initiated, those who fund and those who send terrorists to kill Jews," Sharon said.

Rantisi was the most high-profile Hamas political leader to be targeted by Israel, and the violence threatened a return to the spiral of attack and retaliation that has ruined past peace plans - at a time when both sides are just starting to implement the first stages of the "road map" to peace and a Palestinian state.

Bush "is deeply troubled by the strike," White House spokesman Ari Fleischer said. "The president is concerned that the strike will undermine efforts by Palestinian authorities and others to bring an end to terrorist attacks, and does not contribute to the security of Israel."

Israel insisted Rantisi is an "arch terrorist" whom the Palestinians should have moved against earlier. "He is an enemy of peace, an enemy of everyone who seeks peace in the Middle East," Sharon aide Ranaan Gissin said. "We actually are saving the peace process by trying to take out such people."

He accused Rantisi of plotting an attack by Hamas, Islamic Jihad and the Al Aqsa Brigades on Sunday that killed four Israeli soldiers in Gaza. Palestinians regard Rantisi as a leader of Hamas' political wing, but Israeli officials say he has been involved in the planning and execution of attacks.

From his hospital bed, Rantisi told reporters he was on his way to visit a sick friend when a rocket hit his SUV. He jumped out and threw himself on the ground as the car, driven by his son Ahmad, crashed into a wall, he said.

The car burst into flames and was reduced to a scorched pile of metal. One of Rantisi's bodyguards and a woman bystander were killed. Rantisi was hit by shrapnel in the leg, arm and chest; his son, three bodyguards and 22 bystanders also were wounded, doctors said.

Thousands of Hamas supporters crowded the courtyard outside Shifa Hospital, chanting slogans against Abbas, also known as Abu Mazen. "Abu Mazen, we want resistance," the crowded shouted. Dozens of Hamas gunmen fired assault rifles in the air.

Some Hamas leaders said before Tuesday's strike they were considering resuming truce talks that the group abandoned Friday. After the strike, however, Hamas threatened to resume its campaign of suicide attacks against Israel and even target Israeli politicians, which it has rarely done in the past.

Mahmoud Zahar, a Hamas leader, said there would be quick retaliation: "The Hamas response will be like an earthquake."

"An eye for an eye ... a politician for a politician," he said.

Rantisi said the deaths caused by the strike "deserve retaliation. But we must all remember that our war is not a war of retribution. We are resisting an occupation that has raped the land and sacrificed the holy sites."

"I swear we will not leave one Jew in Palestine," he said. "We will fight them with our might."

Hamas is the largest militant group carrying out bombings and shootings against Israelis. In more than 90 suicide attacks since September 2000 - most by Hamas - more than 350 people have been killed.

Palestinian officials, resisting Israeli pressure to dismantle militant groups until a cease-fire can be worked out, have been pressing Israel not to target militant leaders or launch other crackdowns.

The road map says Israel must refrain from actions that undermine trust, but does not specifically rule out the targeted killings of Palestinian militants. Israel indicated last month it would only use targeted killings as means of last resort to prevent attacks on Israelis.

Israel was sending mixed messages with its actions Tuesday. On the one hand, Israeli troops dismantled 10 uninhabited settlement outposts in the West Bank overnight - as provided by the peace plan.

However, the missile strike threatened to undermine the fragile position of Abbas, who was appointed prime minister April 30 and has no Palestinian support base. Abbas has been criticized by Palestinians for pledging to end the "armed intefadeh" while getting little in return from Israel.

Foreign ministers from eight Arab states, meeting in Bahrain on Tuesday, accused Israel of trying to damage the peace process with the strike. "Israel continues to bomb the Palestinian territories in an attempt to sabotage the peace efforts and bring the region back into the cycle of violence," Arab League Secretary General Amr Moussa said after the meeting.

Even some members of Sharon's coalition condemned the attack.

"That was not a wise action," said Ilan Leibovitch, a lawmaker from the Shinui party. "We are not talking about someone who's wearing an explosive belt and is about to blow himself up in Netanya or Tel Aviv, but rather a man who holds a political position."