Israeli troops have shot dead three Palestinians in a West Bank raid.
Islamic Jihad has been behind two suicide bombings this year
They were shot after they opened fire during an operation directed against Islamic militants in a village outside Tulkarm, Israeli officials said.
Palestinian militants fired a rocket into Israel from Gaza, the military said, in the first such attack since Israel's withdrawal from the region.
Islamic Jihad members said they carried out the attack, which caused no damage or casualties, to avenge the killings.
The rocket landed in a field in southwest Israel, near the border with the northern Gaza Strip.
Israeli military sources said Friday's West Bank raid aimed to capture senior members of Islamic Jihad, which had claimed responsibility for suicide bombings in February and July that killed 10 Israelis.
Palestinian witnesses said that clashes broke out when Israeli jeeps, backed by tanks and helicopters, arrived.
Support for the radical group Islamic Jihad is seen as strong in the West bank village of Illar, near Tulkarm.
Separately, Israeli forces say they arrested an Islamic Jihad man in a raid on the West Bank city of Ramallah.
Meanwhile, Palestinian Authority officials say the Rafah border crossing between the Gaza Strip and Egypt is now open, and will remain so for two days.
The minister in charge of the crossing, Sabri Saidam, said this was to allow people who were trapped outside Gaza to return home; and let those who needed to leave - in order to study, for instance - to leave Gaza.
There were angry scenes on Thursday among the hundreds of Palestinians stuck on the Egyptian side of the border.
It was sealed by Palestinian forces on Monday, after thousands poured across to celebrate Israel's withdrawal from the Gaza Strip.