A 75-year-old woman was hit by shrapnel from an Israeli tank shell fired at her house near the town of Jebaliya.
Later on Thursday, a 12-year-old boy was killed by Israeli gunfire as he stood on the roof of his house at the edge of the Jebaliya camp.
Two civilians, aged 16 and 23, were killed in an air strike in eastern Gaza City.
An 18-year-old man was hit when a tank shell fell near his house in northern Gaza.
Also on Thursday, Israeli troops surrounded a house in the West Bank city of Jenin. Residents said they opened fire at stone throwers, slightly wounding two.
At least 150 Palestinians, about half of them fighters, have been killed since the Israeli assault on Gaza began after the capture of an Israeli soldier by Palestinian fighters in a cross-border raid on June 25.
Wednesday's toll was the highest since Israeli troops returned to the territory last month, less than a year after they withdrew after a 38-year occupation.
Israel's offensive into Gaza to end cross-border rocket attacks has largely been overshadowed by fighting against Hezbollah fighters in Lebanon, but shows no sign of slackening.
Early on Wednesday, tanks and troops pushed into north-eastern Gaza, a stronghold of fighters firing rockets into Israel.
Fighters have also kept up attacks with homemade rockets despite the Israeli offensive.
Israel has rejected demands for a prisoner exchange by the fighters who captured Corporal Gilad Shalit in the raid, in which two other Israeli soldiers and two Palestinian fighters were killed.
Some of those involved in the kidnapping were from the armed wing of the governing Hamas group.