Fighting broke out with renewed ferocity in Gaza on Friday as Israeli forces bombarded the town of Rafah in response to the apparent capture of one of its soldiers by Hamas, after an internationally brokered ceasefire collapsed almost immediately.  Peace talks planned in Cairo to take advantage of the truce stalled before they began, as the threat of a new escalation loomed, possibly involving an Israeli ground assault on Rafah in search of Second Lieutenant Hadar Goldin. His fate was unclear, as Hamas issued conflicting statements about whether it had captured him.  The United States and the United Nations supported Israeli accounts that Hamas had taken advantage of the 72-hour humanitarian ceasefire to ambush Israeli Defence Forces (IDF) soldiers near the entrance to a tunnel outside Rafah, on the southern end of the Gaza Strip on the Egyptian border, killing two soldiers at the same time as seizing Goldin.  Barack Obama said that Hamas should be held responsible for the collapse of the ceasefire on Friday, demanding the militant group immediately release Goldin and insisting the US was doing everything possible to prevent the deaths of Palestinian civilians, which he called "heartbreaking".  Obama strongly condemned the Palestinian side for failing to follow through on a truce which he said ended when militants killed two Israeli soldiers and captured a third "almost minutes after a ceasefire had been announced".  "If they are serious about trying to resolve this situation, that soldier needs to be unconditionally released as soon as possible," Obama told reporters at the White House. However he struck a pessimistic note about the prospects of piecing together another ceasefire after Friday's return to violence, an objective he said the US would continue, acknowledging that ceasing hostilities in the current climate would be "challenging".  "I think it's going to be very hard to put a ceasefire back together again if the Israelis and the international community can't feel confident that Hamas can follow through on a ceasefire commitment," Obama said, adding it was "not particularly relevant" whether or not a Hamas leader - or another militant faction - ordered the abduction. "The point is when they sign on for a ceasefire they're claiming to speak for all the Palestinian factions."  Obama reaffirmed his support for Israel's military attempts to defend itself from Hamas rocket attacks and cross-border assaults using tunnels. "At the same time we've also been clear that innocent civilians in Gaza, caught in the crossfire, have to weigh on our conscience, and we have to do more to protect them," he said.  The president said it was "hard to reconcile" support for Israel's self-defence and concern for the death of innocent Palestinians. He added: "I want to see everything possible done to make sure that Palestinian civilians are not being killed. It is heartbreaking to see what is happening."  The UN secretary-general, Ban Ki-moon, said the Hamas attack was "likely to have very serious consequences for the people of Gaza, Israel and beyond". Through his spokesman, Stéphane Dujarric, Ban said: "Such moves call into question the credibility of Hamas's assurances to the United Nations."  After the clash at the tunnel, Israel struck back with heavy artillery fire and an aerial bombardment of Rafah, killing at least 65 Palestinians, many of them children, and wounding more than 350, according to local health authorities. Reports from the town's al-Najar hospital described bloodied bodies lying on stretchers and across the floor, as family members searched frantically for missing relatives. In 25 days of fighting more than 1,500 Palestinians have been killed, as well as 63 Israeli soldiers and three Israeli civilians.  Several other medical institutions have been forced to close or have been badly damaged during four weeks of war.  The bombardment of Rafah appeared to reflect what the IDF called the "Hannibal directive", in which it responds to any capture of a soldier with heavy fire aimed at stopping the captors leaving the scene, even if it risks injury to the Israeli prisoner.  "Israel will take all necessary steps against those who call for our destruction and perpetrate terrorism against our citizens," Israel's prime minister, Binyamin Netanyahu, told the US secretary of state, John Kerry, in a phone call. Netanyahu convened his cabinet on Friday to decide on a response.  "Hamas, which has security control over the Gaza Strip, must immediately and unconditionally release the missing Israeli soldier," Kerry said in a statement. "The international community must now redouble its efforts to end the tunnel and rocket attacks by Hamas terrorists on Israel."  Britain's deputy prime minister, Nick Clegg, urged Israel to enter direct negotiations with Hamas. Writing for the Guardian, he said: "It is time for the Israeli government to talk to the Hamas political leadership in Gaza."  Clegg has already gone much further than any Conservative government minister by saying Israel's actions appear to be disproportionate and a form of collective punishment.  An IDF spokesman, Lieutenant Colonel Peter Lerner, said the truce was broken at about 9.30am when Israeli soldiers had been preparing to destroy a Hamas tunnel running from Gaza into Israel, as the ceasefire terms allowed, when a group of militants emerged from an underground shaft. Lerner said there was at least one suicide attacker in the assault. There was an exchange of fire, after which Goldin was reported missing.  According to the Haaretz news website, IDF soldiers followed the attackers through the tunnel, which came up in an empty mosque. Special forces were sent in to search the surrounding neighbourhood supported by heavy artillery and warplanes, which caused the high civilian casualties.  The soldier's father, Simha Goldin, a Tel Aviv University professor, issued a brief statement to the media outside his home. "We want to support the military in the fighting against Hamas in Gaza," he said. "We are sure the military will not stop before it turns over every stone in Gaza and returns Hadar home safe and sound."  Moussa Abu Marzouk, a senior official in the Hamas political wing, told Turkish media that an IDF soldier had been taken, but that the attack occurred 90 minutes before the ceasefire came into effect at 8am, and was therefore not a violation. However, subsequent Hamas statements denied having taken a captive.  In the two hours before the truce collapsed, Gazans had emerged from hiding in an effort to restart their lives. In Gaza City fishermen immediately put to sea, cautiously keeping close to the shore, after nearly four weeks without working.  Streets filled quickly. Samira Attar, 27, a housewife sitting in a donkey cart with her husband, five children and three mattresses, said she was heading back to her house in Atattraa, northern Gaza. She had been staying with relatives.  "I am going back to my house for the first time for 17 days," Attar said. "I hope this ceasefire will hold for the 72 hours and longer, God willing. We don't need more bloodshed, or more devastation. I'd like to see Israel be defeated and broken but the circumstances were very difficult."  In Beit Hanoun, a town near the northern border of Gaza that has seen sustained bombardment and fighting, hundreds of families were returning to find their homes. But at about 11am it was clear the ceasefire had broken down. Amid shelling and small-arms fire, families heading back to salvage belongings or see what had happened to their homes rushed for safety.  As reports of fighting and casualties in Rafah started filtering in, the streets of Gaza City began to empty.  The ministry of health in Gaza called for immediate international assistance to evacuate thousands of civilians "trapped under heavy Israeli bombardment" in Rafah. "Some 5km between Salah al-Eddin street and al-Najar hospital is under intense and indiscriminate artillery fire, ambulances are unable to reach the wounded, and thousands of civilians are trapped in their homes. We cannot reach the civilians to evacuate them, the wounded to provide medical care, or the dead to retrieve their bodies," the ministry said in a statement.  Maria-Cecilia Goin, of the International Committee of the Red Cross, said the "humanitarian space" in Gaza was shrinking, with intense fighting in the north, east and south of the strip seriously impeding the organisation's work.  The Israeli soldier missing after being caught in an ambush by Hamas fighters in Gaza is understood to have lived in the UK.  Second Lieutenant Hadar Goldin, a 23-year-old from Kfar Saba, is understood to have spent two spells in Cambridge, where his father worked as an academic.  Rabbi Reuven Leigh, who is a chaplain at Cambridge University and a rabbi in the local community, wrote on Twitter: "Shaken to hear of Hadar Goldin's kidnapping, he spent a few years living in Cambridge with his family, please pray for his safe return."  A friend of the family confirmed to the Jewish Chronicle that Hadar and his twin brother had lived in Cambridge. The friend, who did not want to be named, said the twins' parents were Israeli, and he did not believe Hadar had taken up British citizenship.  Barry Landy, of the Cambridge Traditional Jewish Congregation, told the Chronicle: "Hadar was a nice boy. The first time they came he was 12, the second time he was 15; on the second occasion he did his barmitzvah here. The news is terribly shocking."  Matthew Taylor and Mark Tran
More than 50 Palestinians killed as fate of Hadar Goldin remains unknown following truce-breaking tunnel clash with Hamas