The Palestinian health ministry says 15 Palestinians have been killed in the Gaza Strip where the Israeli military is targeting members of the Palestinian group Islamic Jihad.
A five-year-old child, two women and several PIJ fighters including leader Tayseer Jabari are among the dead.
Some 300 Palestinian rockets and mortars have been fired at Israel since Friday, an Israeli official said.
Israel says it launched the operations due to “immediate threat” from PIJ.
The latest violence is the most serious flare-up between Israel and Gaza since an 11-day conflict in May 2021 left more than 200 Palestinians and a dozen Israelis dead.
The Israeli military is warning this latest operation – codenamed Breaking Dawn – could last for a week.
As well as air strikes on Gaza, some 19 members of PIJ have been arrested in raids across the occupied West Bank, according to Israel.
Sirens warning of incoming missiles continued to sound in Israeli towns on Saturday, amid more reports of air strikes in Gaza.
Palestinian health officials confirmed a man was killed near Khan Younis, in the south of the strip, on Saturday.
But so far Hamas, the biggest militant group in the area which has similar ideology to Islamic Jihad and often coordinates its actions with it does not seem to be firing from its large rocket arsenal.
As a result, there are no reports of Israeli air strikes targeting Hamas, which would mark an escalation in the violence.
Editing by Omotola Oguneye