Updated

Hamas (search) threatened revenge after an Israeli helicopter blew up a car on a busy Gaza City (search) street, killing a Hamas militant who was involved in making and firing rockets at Israeli towns.

Six bystanders were wounded, two of them seriously, hospital officials said.

The missile struck Khaled Abu Shamiyeh (search), 30, as he was riding in his car in Gaza City. Abu Shamiyeh was the head of Hamas in Gaza's Sheik Radwan neighborhood, and was involved in building homemade Qassam rockets, the army said.

Omar Arfa, 52, who owns a fast food stand in Gaza City, said the street was full of cars when the helicopter fired the missile. "A spark came from the sky, then there was a huge explosion in part of street," he said.

Hamas militants gathered at the hospital and called for revenge against Israel. "Hamas will teach the enemy (Israel) a painful lesson," said Hamas spokesman Mushir al-Masri.

Israel has killed dozens of Palestinian militants and scores of bystanders in targeted attacks in four years of fighting. On Sept. 7, helicopters fired missiles at a Hamas training area, killing 14 militants. Hamas has carried out dozens of suicide bombings in Israel.

Hamas and other militant groups have also fired hundreds of highly inaccurate, low-explosive, homemade rockets at Israeli towns and Jewish settlements in Gaza.

Many of the rockets land in empty fields, but two Israelis, including a 4-year-old boy, were killed in one attack. Houses and cars have also been damaged in rocket barrages.

In a separate incident in Gaza on Monday, the Israeli army killed an unarmed Palestinian who was approaching a military outpost near a Jewish settlement, the army said.

Prime Minister Ariel Sharon (search) pledged Sunday at his weekly Cabinet meeting to strike back at militants launching rockets from the Gaza Strip, saying the army would fire at them even if they are in residential areas.

"We have to think about how to act against the sources of the fire, after warning the civilians," Sharon was quoted as saying by Cabinet ministers in the meeting.

Hard-liners who oppose Sharon's "disengagement" plan to withdraw from all Gaza Strip and four West Bank settlements say that a Gaza pullout would put more Israeli cities within range of Palestinian rockets.

Meanwhile, a Gaza settler leader, Avner Shimoni, said settlers slated for evacuation would file appeals against the pullback Monday in Israel's Supreme Court.

The appeals say two recent decisions by the government — to set up a body overseeing evacuation and to pay cash advances to settlers — are illegal. Supreme Court appeals could slow down the withdrawal, to be completed within a year.

Despite hard-line opposition to the pullout, the army and police are completing plans on how to remove settlers from their homes.

The army estimates it will cost US$400 million to evacuate the settlers, move troops to six bases outside Gaza, and install high-tech sensors and cameras on the Gaza-Israel border fence to prevent infiltration by militants, said a defense official, who spoke on condition of anonymity.

The paramilitary border police will be in charge of removing settlers, while soldiers — mainly conscripts — will provide overall security during the evacuation. Army reservists will be sent to the West Bank to take the place of conscripts sent to Gaza for the withdrawal, the official said.

At some point before the start of evacuation, the number of soldiers in Gaza will be doubled, from one to two divisions, the defense official said. One division would deal with settlers, and the second with possible Palestinian violence. A division in the Israeli army generally has thousands of soldiers.