JERUSALEM — Israel’s security cabinet is expected to meet Saturday night to declare a cease-fire in Gaza and will keep its forces there in the short term while the next stage of an agreement with Egypt is worked out.

“It looks as if all the pieces of the puzzle are coming together,” Mark Regev, a spokesman for Prime Minister Ehud Olmert, said Friday. “There will be discussions tomorrow morning, and it looks like a cabinet meeting will take place tomorrow night. Everyone is very upbeat.”

Meanwhile, Israeli tank fire killed two boys at a United Nations-run school on Saturday in the northern Gaza Strip town of Beit Lahiya, a U.N. official told Reuters. Adnan Abu Hasna, a spokesman for the U.N. Relief and Works Agency, said two brothers had been killed and 14 people had been wounded in the attack, including the boys' mother. An Israeli army spokesman said that he was checking the report.

The most promising element for bringing the three-week conflict to a close occurred in Washington on Friday, where Secretary of State Condoleezza Rice and Foreign Minister Tzipi Livni of Israel signed an understanding on a range of steps the United States would take to stem the flow of new arms to Hamas from the Egyptian Sinai, mostly via tunnels.