Medics and relatives said that Saadi Subuh, 23, and Mustafa Abu Zalat, 17, were shot and killed in the refugee camp of Al Faraa on Friday.
The circumstances of shooting were not clear, but Abu Zalat's uncle said his nephew may have been throwing stones at Israeli army jeeps at the time.
In the village of Yamoun, Ahmed Abul Hassan, 28, was shot and killed while he stood on the roof of his home.
Relatives said he had gone up to watch the army raid and was hit by a bullet to the head.
Two of Abul Hassan's brothers were wounded, the family said.
The Israeli army said soldiers fired at two gunmen in Yamoun and hit them.
On Thursday, three Palestinians were killed in the southern Gaza strip during an Israeli incursion into the small town of Abassan.
The killings are part of the ongoing Israeli offensive in Gaza and the West Bank after the abduction of a soldier in a cross-border raid near Gaza on June 25.