Israel says it has resumed air strikes in Gaza after Palestinian militants fired rockets following the end of a three-day truce on Friday morning.
The Israeli army called the renewed rocket attacks “unacceptable, intolerable and short-sighted”.
Palestinian militant group Hamas, which dominates Gaza, earlier rejected any extension of the truce, saying Israel had failed to meet its demands.
Some 1,990 lives have been claimed in four weeks of fighting in Gaza.
Israeli government officials said they had pulled out of Egyptian-brokered negotiations with Hamas and the other Palestinian factions in Cairo, stressing they would not “negotiate under fire”.
But Egypt called on both sides to return to the negotiating table.
On Friday, the Israel Defense Forces (IDF) resumed its offensive on Gaza with aircraft, tanks and gunboats, attacking some 35 targets.
A 10-year-old boy was killed in a strike near a mosque in Gaza City, Palestinian officials told the BBC. Local media reported that an Islamic Jihad militant was killed in a later attack.
The IDF earlier announced it was striking “terror sites across the Gaza Strip” in response to renewed rocket fire.
Militants began firing missiles from Gaza shortly before the ceasefire ended at 08:00 local time (05:00 GMT).
By Friday afternoon, the IDF said more than 52 rockets and mortars had been fired at Israel, injuring two Israelis.
Israel’s Iron Dome missile defence system had intercepted three rockets and 38 had landed in Israel, it added.
The violence resumed after Israeli and Palestinian representatives failed to agree a long-term truce at indirect talks in the Egyptian capital, Cairo.
Hamas said Israel had failed to meet its key demands, including the lifting of the blockade of Gaza and the freeing of about 100 prisoners released in exchange for Gilad Shalit in 2011 who have been re-arrested.
The group also rejected Israel’s call for the demilitarisation of Gaza. A spokesman warned the militant group was ready for “a long war”.
However, Hamas said the Palestinian factions were willing to continue the talks despite the fresh violence.
The Israeli delegation left Cairo on Friday morning.
“Hamas is now continuing to fire towards Israeli civilians, while Israel fully respected the ceasefire and announced it is ready to extend it,” a senior official told the BBC.
On Friday afternoon, Egypt’s foreign ministry called for an immediate resumption of negotiations on a long-term truce, stressing that only a few outstanding issues remained.
“The foreign ministry calls on all sides to rise to their responsibilities… and to return immediately to the ceasefire commitment and exploit the opportunity available to resume negotiations on the very limited sticking points that remain in the fastest possible time,” a statement said.
At least 1,922 Palestinians, mostly civilians, have died, according tolatest United Nations figures.
Israel’s government says 64 soldiers have been killed, along with two Israeli civilians and a Thai national. It also claims that about 900 Palestinian militants have died in the violence.
Israel launched Operation Protective Edge on 8 July with the stated aim of halting rocket fire from militants in Gaza and destroying the network of tunnels it said were used by militants to launch attacks inside Israel.
On Thursday, the human rights group Amnesty International called for an investigation into what it said was mounting evidence that Israeli forces had deliberately attacked hospitals and health professionals in Gaza. The attacks have left at least six medics dead.