Israel said on Friday its fighter jets had bombed the Gaza Strip, in the clearest sign yet the war has resumed with full force after a week-long truce. The announcement came shortly after the ceasefire expired at 05:00 GMT Friday. Earlier Friday, Israel accused Hamas of violating the terms of the ceasefire, including by firing rockets toward Israel from Gaza. The Palestinian militant group did not claim any attack. Minutes after the truce expired, an AFP journalist on the scene said Israeli airstrikes and artillery fire hit Gaza City. Six Palestinians were killed in an Israeli air raid on Rafah, in southern Gaza, according to Gaza"s health ministry. Two children were killed in air raids on Gaza City, a doctor at Ahli Arab hospital told AFP. With the resumption of conflict, Israeli authorities have reintroduced restrictions in force before the ceasefire. In several areas of the country, schools can only open if they have shelter that meets standards. Reflecting the fragile situation, Hamas claimed responsibility for a deadly shooting in Jerusalem on Thursday that killed four Israelis. The Palestinian group nevertheless said it was ready to extend the truce in Gaza, after US Secretary of State Antony Blinken called for the pause to continue. Mediated by the US, Qatar and Egypt, the truce between Israel and Hamas entered into force on 24 November. Some 240 people were taken hostage and brought to Gaza during the 7 October attack. This surprise raid left around 1,200 dead in Israel, mostly civilians. Based on internal documents, the New York Times claimed on Friday Israeli officials had obtained Hamas" plan more than a year in advance to carry out an unprecedented attack against Israel, but judged this scenario unrealistic. According to Palestinian officials, more than 15,000 people, including at least 6,150 children and young people under the age of 18, died in Israeli strikes. The Hamas-controlled Government Media Office has blamed the United States and the international community for the resumption of fighting in Gaza after a week-long truce between Israel and Hamas broke down Friday. The ministry said that America and the international community “bears responsibility for the crimes of the ‘Israeli’ occupation and the continuation of the brutal war against civilians, children and women in the Gaza Strip.” The statement added that Palestinians had a right to defend themselves “by all means” and to establish a Palestinian state with Jerusalem as its capital. Sirens went off in Israel in the hour before the truce was due to expire Friday morning, warning of an incoming rocket which was intercepted. Sirens have continued in Israeli communities around Gaza since. "Sleeping Israelis once again woke up to the sound of the red siren of Hamas rockets falling at us once again from Gaza," Israeli military spokesperson Maj. Doron Spielman told CNN, adding that "there have been multiple rockets" that were intercepted Friday. The Israeli military resumed fighting in Gaza after the militant group broke the outline of the truce, Israeli Prime Minister Benjamin Netanyahu said in a statement released from his office Friday. Hamas “didn’t respect its obligation to release today all the abducted women and launched rockets toward the citizens of Israel," Netanyahu said. With the return of the combat mission, the “government of Israel is obliged to accomplish the targets of the fighting," according to the prime minister. He said those targets are “to release the hostages, to liquidate Hamas” and to ensure the citizens of Israel are never again threatened by an attack from Gaza. Hamas was also defiant. "What Israel did not achieve during the fifty days before the truce, it will not achieve by continuing its aggression after the truce," Ezzat El Rashq, a member of the Hamas political bureau, said on the group"s web site. Palestinian media and Gaza"s interior ministry reported Israeli air and artillery strikes across the enclave after the truce expired, including in Rafah, near the border with Egypt. In Khan Younis, in the southern Gaza Strip, a Reuters witness said he could hear heavy shelling and see smoke rising in the east of the town. People were fleeing the area to camps in the west of Khan Younis for cover, he added. Al-Jazeera reported a number of people had been killed and injured by Israeli raids and shelling. Qatar and Egypt had been making intensive efforts to extend the truce following the exchange on Thursday of the latest batch of eight hostages and 30 Palestinian prisoners. Thursday"s releases brought the totals freed during the truce to 105 hostages and 240 Palestinian prisoners. One of Qatar"s lead negotiators, career diplomat Abdullah Al Sulaiti, who helped broker the truce through marathon shuttle negotiations, acknowledged in a recent Reuters interview the uncertain odds of keeping the guns silent. "At the beginning I thought achieving an agreement would be the most difficult step," he said in an article that detailed the behind-the-scenes efforts for the first time. "I"ve discovered that sustaining the agreement itself is equally challenging." The truce had allowed some humanitarian aid into Gaza after much of the coastal territory of 2.3 million people was reduced to wasteland in the Israeli assault. More fuel and 56 trucks of humanitarian supplies entered Gaza on Thursday, Israel"s defence ministry and the Palestinian Red Crescent Society said. But deliveries of food, water, medical supplies and fuel remain far below what is needed, aid workers say. At an emergency meeting in Amman, Jordan"s King Abdullah on Thursday urged UN officials and international groups to pressure Israel to allow more aid into the beleaguered enclave, according to delegates. — Agencies