The bloodshed broke out hours before Israeli Prime Minister Ariel Sharon was to leave for the US capital to hold talks with President George W. Bush, who was also conferring with his Egyptian counterpart, Hosni Mubarak.
An Israeli man and his pregnant wife were shot dead by two men who stormed into the Jewish settlement of Karmei Tzur, near the southern West Bank town of Al Khalil, and opened fire, the Israeli army said.
Another Israeli was also fatally wounded and five others injured in the pre-dawn attack on a cluster of vans north of Al Khalil by the gunmen armed with assault rifles and grenades, the military said.
One of the Palestinians was killed by return fire while the other fled towards the nearby town of Halhul, a spokesman said.
Israeli forces sealed off the area while tanks and troops moved into Halhul and the town of Beit Ummar, going door-to-door and rounding up Palestinians for interrogation.
Four Palestinians were killed in two foiled attacks on the Gaza Strip, an Israeli military spokesman said.
At Sufa, in the southern Gaza strip, the Israeli army discovered the bodies of two Palestinians apparently killed by an explosion near the electronic barrier that separates the region from Israel.
The armed wing of the radical Palestinian group Hamas claimed responsibility for the attack in an announcement over a loudspeaker in the town of Rafah and said three of its men were killed.
An Israeli naval shore unit fired on two other Palestinians as they attempted to swim ashore near the northern Gaza Strip settlement of Dugit, the army spokesman said.
The body of one man was recovered along with a bag containing two Kalashnikov rifles, ammunition and four handgrenades. The fate of the second man was not known.—AFP