A Gaza security chief loyal to moderate President Mahmoud Abbas was killed when his car blew up Wednesday, the second attack on security commanders in the volatile area in less than a week.
It was not immediately clear who planted the bomb that killed Nabil Hodhod, head of the elite Preventive Security Service in central Gaza.
Security officials said Hodhod had just gotten into his car when a bomb went off. Hodhod was killed and his deputy wounded by the blast, the officials said.
The attack came during an increasingly bloody power struggle between the Hamas government and Abbas.
Earlier in Gaza masked gunmen seized three Hamas militants outside a mosque, shot them and dumped them with stomach and leg injuries at a gas station. One of the Hamas men later died of his wounds at a hospital.
In Gaza City, hundreds of gunmen loyal to Hamas marched through the streets in military-style formation in a new display of force, raising assault rifles and small copies of the Muslim holy book Koran.
In the West Bank, an Israeli arrest raid turned violent. Soldiers shot and killed three Palestinians and wounded 34 others, Palestinians said, before the Israeli forces left the West Bank city of Ramallah with the militant, Mohammed Shubaki, an Islamic Jihad leader.
Palestinian police said an undercover Israeli unit driving a Ford sedan was fired on by militants, and set on fire. The army said its forces were confronted by a huge riot and gunfire.
Television footage showed the streets of central Ramallah deserted except for a few jeeps, as smoke rose from nearby buildings.
And in Israel, top aides to Prime Minister Ehud Olmert said after his meeting with U.S. President George W. Bush that Israel would give the Hamas government until the end of the year to moderate its position. If Hamas refuses, as it has done so far, Israel will go ahead with what one adviser said would be a "broad" pullback from the West Bank. Israel plans to hold on to major West Bank settlement blocs in drawing its own borders.
In a new twist, a 1,000-strong unit of gunmen made its debut Wednesday, marching through Gaza City in black T-shirts and bandanas. They professed support for the Hamas militia, even though the logos on their T-shirts identified them as Fatah loyalists.
Fatah immediately distanced themselves from the unit. The new unit's commander, Khaled Abu Hilal, is a former Fatah member who has since been disowned by the group and serves as spokesman of the Hamas-controlled Interior Ministry.
Hamas, meanwhile, held Fatah gunmen responsible for the deadly shooting Wednesday near the southern Gaza town of Khan Younis. Hamas said the kidnappers were also members of the Preventive Security Service, a security branch allied with Abbas.
The incident began after morning prayers when the three Hamas militants emerged from a mosque. A car with masked gunmen pulled up, bundled the Hamas members into the vehicle and sped off, Hamas officials said.
About 15 minutes later, the three Hamas men were found lying in the street, near a gas station. Two had been shot in the legs and the third in the abdomen and leg. Hamas officials said the man with the stomach and leg injuries died at a nearby hospital. He was identified as Salem Kadih, 22.
In Israel, Justice Minister Cabinet Haim Ramon said Israel will move with plans to draw its final borders if Hamas does not recognize Israel and renounce violence within six months.
Ramon, a close Olmert associate, spoke just hours after Bush referred in surprisingly warm tones to the Israeli leader's plan to withdraw unilaterally from chunks of the West Bank. Bush called the idea "an important step" toward peace.
Ramon reiterated that Hamas must recognize Israel, accept past peace agreements and renounce violence before peace talks can begin. "If these things don't happen, we won't wait for years, but rather we will wait until the end of this year," Ramon told Israel Radio. "This will be a year of diplomacy."
"First negotiations, and after the negotiations, if it doesn't succeed and it becomes clear that there is no (Palestinian) partner, we will move ahead with the consolidation plan," Ramon said, referring to the withdrawal.
Dov Weisglass, one of Olmert's most senior advisers, said that if negotiations fail, "Israel will carry out a broad unilateral process that will in the end leave in Israel's hands the ... large settlement blocs." Weisglass spoke to Israel Army Radio from Washington.
In another interview, with Israel Radio, Weisglass said that Israel will have contacts with the moderate Abbas, but will not hold peace talks with him unless Hamas changes its positions.
"There can be other talks, coordinating different issues, regarding daily coexistence between us and the Palestinians and there are many such issues. Something like this will certainly occur," Weisglass said.
"Peace negotiations with the Palestinian Authority or any of its authorized organs ... can only occur when the Palestinian Authority is no longer a Hamas authority," Weisglass added.