Reporting from Jerusalem—
The toll on civilians from violence between the Israeli military and militants based in the Gaza Strip rose Monday as three Palestinians — a 15-year-old boy on his way to school and a father and daughter walking in the street — were killed by Israeli airstrikes, Palestinian officials said.

Militants from Islamic Jihad and the Popular Resistance Committees on Monday fired rockets into southern Israel, hitting an empty kindergarten and damaging a residential structure in the city of Ashdod, injuring an elderly woman and another person with shrapnel. At least eight other people were treated for hysteria, officials said. No Israelis had been killed.

Militants also had expanded their targets slightly farther north toward Tel Aviv.

An Egyptian security official, speaking on condition of anonymity, said Egypt had mediated a cease-fire between the Palestinians and Israel that went into effect at 1 a.m. Tuesday, according to wire services. He said the Palestinians agreed to stop launching rockets, and Israel agreed to stop targeting militants in airstrikes. Neither Palestinian militants nor Israel would immediately comment amid the worst flare-up along the Israel-Gaza border since August.

The three civilian deaths Monday, combined with the killing of four militants, brought the Palestinian death toll to 25 since Friday. Dozens of Palestinians have been injured, officials said.

Mohamed Hasoumi, 65, and daughter Fayza were killed by an Israeli missile as they walked in the town of Jabaliya near an area used by militants to fire rockets, Palestinian officials said. Nayif Shaaban Karmout, 15, was killed on his way to school when he was hit by shrapnel, Palestinian media reported.

Israeli military officials denied they carried out any operation near the area where the boy was killed.

Israeli cities near the Gaza border were on high alert Monday, with schools and many businesses closed and residents staying close to bomb shelters.

Some Israeli leaders called for the military to take stronger action to halt the rocket fire.

The latest round began Friday after Israeli forces killed a top militant leader in Gaza as he was driving in his car with an aide.

"The situation is intolerable," Yitzhak Aharonovitch, minister of public security, said Monday on Israel Radio.

"One million Israelis cannot be confined to bomb shelters for four days. Israel must strike with a heavy blow so that once and for all rocket fire to Israel stops."

But experts said a ground operation in Gaza was unlikely at this time given Egyptian opposition to such a move.