Gaza City: Hamas on Saturday warned Israel of "consequences" after its latest air strike on Gaza killed three members of the radical Islamist group`s armed wing.
Medical staff and witnesses said earlier one Palestinian was also wounded in the air strike in the southern Gaza Strip.
They said the target was a car driving between the town of Khan Yunis and the Deir al-Balah refugee camp.
Witnesses said they saw three charred bodies dragged from the burnt-out vehicle.
An Israeli military spokesman said the raid, planned jointly with the Shin Bet domestic security agency, was a pre-emptive strike against militants planning to kidnap Israelis during the coming Jewish festival of Passover.
"An Israel Air Force aircraft hit a Hamas terror cell... planning to carry out kidnapping attacks in the Sinai Peninsula and in Israel during the Passover holiday," he said.
The Sinai coast of neighbouring Egypt is a popular destination for Israelis during the week-long holiday which begins on April 18 and commemorates the biblical Exodus of the Israelites from Egypt.
Hamas said in a statement the three dead were members of the Islamist group`s Ezzedine al-Qassam Brigades.
Hamas identified them as Ismael Lubbad, Abdallah Lubbad and Mohammed Eldayah.
The air strike is a "serious escalation" and Israel "will bear all the consequences", the Brigades warned.
Israeli public opinion is still inflamed over the capture by militants of Israeli soldier Gilad Shalit in a cross-border raid into Israel in 2006.
Shalit is still missing, believed held somewhere in the Gaza Strip.
On Wednesday, an Israeli air strike on southern Gaza killed an Islamic Jihad militant and wounded another, but generally the past few days have seen a return to relative calm after a spate of Palestinian rocket attacks into Israel and Israeli counterstrikes on Gaza.
The spate of tit-for-tat violence began on March 16 when a rocket fired from Gaza landed in an open area in southern Israel, without causing casualties or damage.
Within hours, the Israeli air force hit back, killing two militants from the Ezzedine al-Qassam Brigades, in what some saw as a disproportionate response.
Two days later, Hamas militants responded, firing a barrage of around 50 mortar shells at the southern Israeli city of Beersheva in the fiercest bombardment in two years.
On Sunday, the Israeli military made a trial deployment outside Beersheva of the first batteries of its "Iron Dome" short-range missile defence system.
But officials said that the multi-million dollar system, the first of its kind in the world, could not yet provide complete protection from all the rockets and mortar bombs fired from Gaza into Israel.
Each battery comprises detection and tracking radar, state-of-the-art fire control software and three launchers, each with 20 interceptor missiles, military sources said.
Despite the spike in tensions, both Israel and the militant Islamic Hamas, which rules Gaza, appear reluctant to be dragged into another bloody confrontation along the lines of the December 2008-January 2009 war, which killed more than 1,400 people, the vast majority Palestinians.