As US officials work to determine the whereabouts of 14 US citizens unaccounted for since last Saturday’s deadly Hamas assault on Israel, US families of the dead or missing are describing their loss. At least 22 Americans are known to have died in last Saturday’s attacks, and officials have said they are working to determine whether those missing have been killed or taken hostage. Joe Biden, who spoke to relatives of the missing on Friday, said the families were “going through agony not knowing the status of their sons, daughters, husbands, wives children. You know it’s gut-wrenching.” The US president said he was working closely with Israel and other allies and pledged to do “everything possible to return every missing American” held by Hamas. “We’re not going to stop until we bring them home,” he said. Jonathan Dekel-Chen has not heard from his son, 35, since Saturday morning, when Hamas gunmen stormed the Nir Oz kibbutz. There is currently no information on the whereabouts of Sagui, a dual Israeli-US citizen from Connecticut. “He’s a loving guy, funny and charming, a deep thinker, a loving son and a beautiful father, an imaginative and creative doer of the things that get into his head,” he said. Dekel-Chen said he understands that at about 6am the kibbutz was overrun by around 100 Hamas militants. Sagui, he said, hurried to get families into bomb shelters as the men did their best to repel the attack. The Israeli army did not arrive until mid-afternoon. Of 400 people who lived in the village, 240 were dead or missing. Dekel-Chen said Hamas used stolen vehicles and tractors to transport a dozen people to Gaza. Some could be tracked on the cellphones but several dozen others have simply disappeared. Dekel-Chen said: “Sagui is one of those people – he didn’t simply evaporate. We’ve had no word from the Israeli or US government.” As a historian at the Hebrew University of Jerusalem, who has held fellowships at Columbia, among others, Dekel-Chen said he believes the events of last Saturday leave no room for interpretation. He said: “This was mass murder. There can be no grey area about Hamas – what it is, what it’s working toward, why it exists. The grey area is gone. This is the first time a government has set out to organize, train and execute a mass murder on this scale and with this ferocity. “As a peace-maker, which I am, there is simply no way to tolerate it. The people of Gaza are now captives as much as our Israeli captives. The only way peace can even be dreamed about now is by eradicating Hamas. Anyone who finds even a little light in the argument against Hamas is either a fool or an antisemite.” Hayim Katsman, a dual US-Israeli citizen, was initially thought to have been taken to Gaza but was later found killed in his home on Kibbutz Holit. It is understood that that Katsman, 32, shielded a neighbor from Hamas bullets, and that neighbor later saved two children. Katsman, whose grandmother fled Nazi Germany and whose grandfather survived the Holocaust, wrote his doctoral thesis at the University of Washington on “Religious nationalism in Israel/Palestine”. Instead of staying in the US, Katsman moved to the kibbutz, where he worked as a landscaper. His mother, Hanna Katsman, who buried her son on Thursday evening, said: “He was always in a good mood and really enjoyed being with people. It was honorable to me how he did his scholarship but he could also forget about it, hang out and play music.” Katsman was involved in peace initiatives, including Mahsom Watch, which monitors the impact of government activity on Palestinian lives. His sister, Noy, an activist with the Israeli-Palestinian grassroots group Standing Together, told the Jewish Forward that her brother’s death should not be used to justify retribution, a view their mother shared: “She said Hayim wouldn’t have wanted his death to be used against innocent people.” Rachel Goldberg last saw her son Hersh Goldberg-Polin, 23, at 11pm the night before the attack, when he left the house with his friend and some camping equipment to go to do “something fun”. Goldberg was at home in Jerusalem when she woke to the sound of rocket-warning sirens. When she turned on her phone, she saw two text messages from him that read “I love you” and “I’m sorry”. “I immediately know something horrible was happening,” said Goldberg. Her daughter searched online and the news that the Supernova music festival had come under attack. “So we knew immediately where he was but we couldn’t reach him,” she said. In the days since, his mother has tried to piece together some of what happened. Goldberg-Polin, she said, and three friends had got into a car to try to escape the massacre. “Rockets started falling into the street. It was complete chaos. So they stopped and went into a roadside bomb shelter. Hamas terrorists came, threw in hand grenades and spraying it with machine-gun fire. A total horror.” She said her son was trying to throw the grenades out as fast as they came in. After a lull, the terrorists came in and ordered the survivors to stand up. Most people were dead; some were alive but played dead and some alive but badly wounded. Goldberg-Polin stood up. “The witness we spoke to said Hersh’s arm below the elbow had been blown off, and he’d taken off his shirt to make a tourniquet. He walked out and they put [him] in a pickup and [he was] taken to the Gaza border,” said Goldberg. His phone last pinged at 12.45pm on Saturday at the border. “We know nothing about him since, except that he has a critical wound that needs medical assistance immediately, if he is still alive,” said Goldberg. Asked if she was worried that Israel’s bombing of Gaza might diminish her son’s chance of survival, Goldberg said she was not thinking of that. “Right now, there is such horrible fighting going on down there, so we’re just trying get any help, clarity or answer that we can,” she said. The top floor of her home is filled with families whose children are fighting. “The country is at war. It’s complete chaos and pandemonium, and it’s a terrible situation. I think this country’s life is at stake. My husband and I recognize that Hersh is the most import priority to us – he’s our world – but there’s a larger picture here, and we’re trying to be mindful of that.”