Aljazeera reported two Palestinians were killed early on Tuesday in Hebron and Qalqilya.
Quoting Palestinian sources, the station said Israeli forces detained and then killed two other Palestinians in Gaza Strip. It said the the dead bodies were found near al-Buraij refugee camp, south Gaza.
One Palestinian was killed during the Israeli invasion into the West Bank cities of Ram Allah and al-Beera on Tuesday.
An Israeli military source has confirmed the first two killings. Describing the men as militants, the source in Jerusalem said they were killed while trying to escape after being told to stop for identity checks.
In the first case the Palestinian, said to be linked to Yasir Arafat's Fatah movement, was found to be carrying a pistol and spare magazines, said the source. The second Palestinian was described as a militant of the Popular Front for the Liberation of Palestine.
There has been no independent confirmation of the killings or of the alleged links to the organisations.
According to a count by the AFP news agency, the latest deaths mean a total of 3567 people have been killed since the start of the Palestinian intifada in September 2000, including 2655 Palestinians and 846 Israelis.
Also overnight in the West Bank, 18 wanted Palestinians were arrested, the military source said. He added that four were activists of the Islamic Jihad movement and another was found to be in possession of a machine gun and magazines.