A brief three-day peace crumbled Friday after militants in Gaza fired dozens of rockets at Israel and Israeli forces responded with their own salvos, including an airstrike near a mosque in Gaza that killed a 10-year-old boy.

By nightfall Friday, Gazan militants had fired 51 rockets and mortars at Israel and Israeli forces had hit 47 targets in the coastal enclave, according to a tally by an Israeli military spokesman.

In Cairo, high-level talks to end the month-long war stumbled, with mixed messages issued that offered little confidence that a deal was near.

U.N. Secretary Ban Ki-moon expressed “deep disappointment” over the failure to extend the truce, which ended Friday morning, and said “the extension of the cease-fire is absolutely essential for talks to progress.”

“The United States is very concerned about today’s developments in Gaza,” White House press secretary Josh Earnest told reporters Friday. “We condemn the renewed rocket fire, and we are concerned about the safety and security of civilians on both sides of that conflict.”

The Islamist movement Hamas, which controls the Gaza Strip and is considered a terrorist organization by Israel and the United States, issued statements through its military wing that it would continue to fight until its demands for more open borders, more freedom of movement and trade, the release of Palestinian prisoners, and the construction of seaports and airports were met.

On Thursday night, a spokesman for Hamas’s military wing essentially warned his political leaders that they should pack up and come home unless there is more progress in Cairo.

Hamas spokesman Sami Abu Zuhri said late Friday: “We think Israel is dragging its feet. They did not respond to our demands and have not done a thing to show that there is a reason to extend the cease-fire.”

Mkhaimer Abusada, a political scientist at Al-Azhar University in Gaza City, said, “The Palestinian side feels it can’t extend the cease-fire without getting something, some positive results.”

The talks in Cairo are being brokered by Egypt and its security apparatus, led by a government dominated by military leaders who are hostile to Hamas. American and European diplomats are struggling to exert influence in talks that have produced only pauses in the violence.

A high-level military delegation from Israel left Cairo early Friday. Israeli authorities declared that they would not talk peace while under hostile fire.

The Egyptian Foreign Ministry said in a statement that the negotiations were progressing and that there only remained “a few, limited points” to sort out.

Children paying a terrible price in Gaza

Few diplomats voiced such optimism in public.

“I think Hamas has nothing to lose. They have to show something, or they have lost,” said Kobi Michael, a former deputy director general at Israel’s Ministry of Strategic Affairs.

Michael said Hamas is in “a very difficult position” because “Egypt is very tough now with Hamas” as its new military-led government is more closely allied with Israel than with the Gaza movement.

Michael added: “Israel is very frustrated, very angry, and the Israelis are calling for retaliation, for dealing with this, ending this rocket fire from Gaza, in a very, very harsh manner.”

Prime Minister Benjamin Netanyahu instructed the Israel Defense Forces (IDF) on Friday to “respond forcefully to Hamas’s violation of the cease-fire.”

Economy Minister Naftali Bennett said: “While the world is busy establishing commissions of inquiry against Israel, our children in the south live under rocket barrages. I will say something simple: We have to determine this campaign alone, whether Ban Ki-moon likes it or not.”

On Friday, families in Gaza began fleeing areas close to the Israeli border, fearing Israeli airstrikes and artillery. Cars and trucks filled with women and children sped toward the center of Gaza City. Horse carts and pickup trucks were topped with mattresses and suitcases.

Shortly before noon, an Israeli airstrike hit a half-constructed mosque in the Sheik Radwan neighborhood, killing 10-year-old Ibrahim Dawawsa, relatives said. The attack injured six others, they said.

Ibrahim was the first casualty after the cease-fire ended. He had gone to the mosque, which is steps away from his home at the end of a narrow street, to play before Friday prayers, said his father, Zuhair Dawawsa.

“When they hit the mosque, I ran out to see what happened,” Dawawsa said, openly in tears. “We found him on the ground, half his brain was outside his skull.

“Who could have expected this?” he continued. “They are still negotiating in Egypt. They are monsters. They couldn’t wait.”

The father also blamed Arab nations for abandoning the Palestinians. But he refused to place any blame on Hamas or other Palestinian factions for firing the rockets into Israel.

Ironically, Ibrahim’s family are supporters of Fatah, the party headed by Palestinian Authority leader Mahmoud Abbas and the very people Israel and the United States hope will enter Gaza after a peace deal is signed and provide a counter-balance to Hamas.

At Ibrahim’s funeral, an imam told the mourners: “We want freedom, we want our dignity. We will not surrender. We are not going to raise the white flag. We are not asking the impossible. Yes, the whole world is against us. But don’t panic, Allah is with the Palestinian people.”

At the cemetery, Ibrahim’s father watched as relatives buried his son. As they placed the last slab of concrete to cover the grave, an Israeli F-16 flew by and fired at a target a few miles away. A huge ball of thick smoke rose above the Gaza skyline.

Among the wounded in Gaza were five other children, health officials said.

Israeli police reported that two Israelis were wounded by Palestinian rocket fire.

“The renewed rocket attacks by terrorists at Israel are unacceptable, intolerable and shortsighted,” said Lt. Col. Peter Lerner, an Israeli military spokesman. “Hamas’s bad decision to breach the cease-fire will be pursued by the IDF. We will continue to strike Hamas, its infrastructure, its operatives and restore security for the state of Israel.”

Strategic Affairs Minister Yuval Steinitz said Friday on Army Radio that Israel would have to “seriously consider” sending troops back into the Gaza Strip “to topple the Hamas regime.”

Orly Halpern in Jerusalem contributed to this report.