A top leader of Palestinian militant group Islamic Jihad, a Hamas ally, and his sons were also killed today in Israeli attacks, Gaza emergency services officials said.
Salah Hasanein and his sons, 12 and 15, were killed in the strike in the southern city of Rafah, they said.
Another raid killed a 23-year-old pregnant woman in the central Gaza town of Deir al-Balah after her house was hit. However, surgeons saved the life of the woman's unborn child.
Meanwhile, Israeli forces were put on high alert for possible clashes in Al-Aqsa mosque in Jerusalem during Friday prayers marking the final stretch of the month of Ramadan.
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The Israeli move came after two Palestinian protesters were killed and many others injured in clashes with Israeli police north of Jerusalem yesterday. Protests were also held in Ramallah, Nablus, Bethlehem and Jerusalem neighbourhoods.
Israeli offesive overnight killed 42 Palestinians, as international efforts for a ceasefire intensified after over 15 Palestinians died and 200 others injured in an Israeli strike on a UN-run school in Hamas-ruled northern Gaza Strip.
According to the UN, more than 118,000 people are now sheltering in UN schools and people are running out of food.
Palestinian toll now stands at 815 killed and more than 5,000 injured. Thirty two Israeli soldiers, two civilians and a Thai worker in Israel have also been killed in the conflict. One other soldier remains missing, but is presumed dead.
In a statement, Israeli Premier Benjamin Netanyahu said he regretted each Palestinian civilian death, but said they were "the responsibility of Hamas".
"We are continuing Operation Protective Edge at full strength, in the air and on the ground," he said at the opening of a special cabinet session.
"Hamas has demands from here to Vladivostok," Netanyahu was quoted by the Jerusalem Post as saying.
Efforts to bring about a ceasefire has so far yielded no results amid a flurry of diplomatic initiatives.