CNN — Deborah Matias, an American citizen who lived in Israel, was shot and killed by Hamas gunmen while shielding her teenage son from their bullets, her father told CNN.

Hayim Katsman, an Israeli-American academic, was hiding in a closet with his neighbor when he was fatally shot, his sibling said.

They are among at least 11 US citizens who were killed in Israel after the Gaza-based militant group launched a devastating attack early Saturday that left at least 900 people there dead.

There are also Americans who remain unaccounted for, President Joe Biden said in a Monday statement, adding it is “likely” some are among those being held hostage by Hamas.

In response to the attack, Israel has pounded Gaza with airstrikes, displacing more than 100,000 people. More than 760 Palestinians have been killed, according to Gaza’s health ministry, and medical care has been hampered by Israel cutting power to the territory. It’s unclear whether any US citizens are among those killed or injured in Gaza.

As families in the US wait for information about their missing loved ones, others are confronted with the sudden loss of siblings, children or parents.

A teen laid under his mother’s body

Ilan Troen said he was on the phone with his daughter when she was killed.

Troen, a professor emeritus from Brandeis University in Massachusetts, said his daughter and son-in-law, Deborah and Shlomi Matias, were killed by Hamas militants over the weekend. Troen’s grandson, 16-year-old Rotem Matias, was shot but will survive, Troen told CNN’s Poppy Harlow on Monday.

“We were on the phone with Deborah as she was killed,” Troen said. “We were on the phone the entire day with our grandson, Rotem, as he lay first under her body, and then found a place to escape under a blanket in a laundry.”

Rotem was shot in the stomach, Troen said, but will recover.

“The brunt of the shot was borne by his mother,” he said. “The terrorists who came, they had explosives and blew up the front door to their house and then blew out the front door to their so-called safe room.”

Rotem hid for more than 12 hours after he was shot, texting on his phone to communicate with people who were coaching him on how to breathe and how to manage “the blood that was coming out of his abdomen,” Troen said, adding Rotem’s phone was down to a 4% charge when he was rescued

Deborah Matias attended the Rimon School of Music in the Tel Aviv area, where she met her husband, Troen told CNN. “Deborah was a child of light and life,” Troen said. “She, rather than becoming a scientist or a physician, she said to me one day, ‘Dad, I have to do music, because it’s in my soul.’”

An academic who was ‘pro-peace’

Hayim Katsman was “very pro-peace” and had supported “a solution for this bleeding conflict” between Israel and Palestinians before he was killed, his sibling told CNN.

Noy Katsman – who is non-binary and uses they/them pronouns – said they last heard from their brother Saturday morning when he wrote to say there were terrorists in Kibbutz Holit, which is in southwest Israel near Gaza.

When they tried to reach their brother again about four hours later, there was no response.

Hayim Katsman’s friend, Avital Alajem, described how she was hiding inside a shelter’s closet with Katsman when gunmen came and began firing at the door – striking Katsman multiple times.

“He was murdered,” Alajem told CNN’s Anderson Cooper in Israel early Tuesday. “I was saved because he was next to the door, and they shot him.”

Katsman was remembered by his sibling as a “brilliant academist,” a musician who DJ’d and played bass, and a volunteer at the community garden in the city of Rahat.

Noy Katsman said their parents moved to Israel from the United States more than three decades ago and their brother was a US citizen.

Hayim Katsman earned his PhD in international studies from the University of Washington’s Henry M. Jackson School of International Studies in 2021 and was described as “an emerging scholar in the field of Israel Studies,” in a statement issued by the Association for Israel Studies.

Noy Katsman told CNN they hoped their brother’s death will not be used “as an excuse to kill other innocent people,” adding: “He wouldn’t have wanted that.”

Families of missing Americans plead with US government for help

The families of Americans who are missing pleaded with the US administration to help locate their loved ones and bring them home during a press conference from Israel Tuesday.

“I love you. I’m sorry,” are the last messages 23-year-old Hersh Goldberg-Polin sent to his parents before they lost contact with him, his parents said during the news conference in Tel Aviv. The police told them their son’s phone signal was located around 12:45 p.m. Saturday on the Gaza-Israel border.

Goldberg-Polin had been at the Nova musical festival earlier that day when Hamas attacked, and he hid with other attendees in a bunker. He helped to throw incoming grenades out of the shelter, his parents said they learned from witness accounts.

“They were fish in a barrel, sitting in this bomb shelter,” said Goldberg-Polin’s mother, Rachel Goldberg.

“Unfortunately, what we found out about Hersh from these eye-witnesses is after this gunfire situation – sometime around 8 or a bit after 8 – Hersh’s arm was blown off from his elbow down,” she said.

Those who could walk were told to walk out of the shelter and were put on a truck and driven away by Hamas, Goldberg-Polin’s parents said.

The family moved to Israel in 2008 but still has American citizenship.

“And so, what I’m hoping is that the powers that be, wherever they are – the American government or anywhere around the world – can see to it that this civilian American who is critically wounded is tended to,” Goldberg said.

Nahar Neta said his 66-year-old mother, Adrienne Neta, was sitting on the porch of her home in Be’eri kibbutzwhen Hamas attacked. Neta said his mother was on the phone with his siblings when intruders barged into her home. They heard screaming through the phone and haven’t heard from her since.

“It is our hope – which is a little bit ridiculous at this stage to say – but the optimistic scenario here is that she’s held hostage in Gaza and not dead on the street of the kibbutz where we grew up,” Neta said.

Rubi Chen has not heard from his 19-year-old son Itay Chen since Saturday. His son is a reservist in the Israeli military who was serving on the Gaza border over the weekend and is now considered missing in action, Chen said. His son elected to be on the base last weekend, so he would be free to celebrate his younger brother’s bar mitzvah next weekend, Chen added.

Chen said he considers his son a prisoner of war and pleaded with the US administration to do what it can to help.

“I’m asking the US not to take a back seat,” he said.

Jonathan Dekel-Chen also called on the US government to help negotiate the release of his 35-year-old son, Sagui Dekel-Chen and other people presumed kidnapped by Hamas.

“The United States administration and its various services have relationships in the world with countries that Israel does not, and it could be helpful for the United States in its various parts to engage with those friends and acquaintances to help it negotiate in some way, secure the release or at least get solid information…” Dekel-Chen told CNN’s Becky Anderson.

His son is the father of two girls and his wife is pregnant with a third daughter, Dekel-Chen said.

According to Jonathan Dekel-Chen, 400 people made up the Kibbutz Nir Oz community before the attack, but he currently knows of only 160 survivors

“The rest have either died or are, as we said, prisoners who are missing,” he said.

US officials are working with Israeli authorities to learn more about the whereabouts of Americans who remain missing and to confirm reports of those being held hostage, President Biden said Monday

Other US citizens missing

Other American families are hoping to hear word of their loved ones.

Born in Los Angeles, Danielle Ben Senior is a 34-year Israeli-American citizen who lived most of her life in Israel, according to her father. Danielle was working at the Nova festival with a group of event organizers, her father said.

Jacob Ben Senior said he has been calling her phone since Saturday morning but has not been able to reach her.

A mother and daughter from the Chicago area who were visiting relatives in Israel are also missing and it’s feared they are being held hostage, a family member told CNN.

US citizens Judith Tai Raanan and Natali Raanan were visiting relatives in Nahal Oz, a kibbutz that was attacked by Gazan militants on Saturday. The family said they are in touch with the US Embassy.

Judith Raanan’s brother Adi Leviatan said he suspected the pair was taken hostage after not hearing from them since the weekend. Natali and Judith arrived in Israel on September 2, he said.