JERUSALEM (AP) — The mother of a young Israeli woman held by Hamas appealed for her release on Tuesday, calling the seizure of some 200 hostages by the Palestinian militant group “a crime against humanity.”

A day earlier, Hamas’ military wing released a video showing a dazed Mia Schem, 21, having her arm wrapped with bandages. It was the first sign of life from any of the hostages since Gaza-based gunmen smashed through border fortifications on October 7, killing more than 1,400 people in Israel.

“I didn’t know if she’s dead or alive until yesterday,” her mother, Keren Schem, said at a news conference. “All I knew is that she might be kidnapped. I’m begging the world to bring my baby back home. She only went to a party, to a festival party to have some fun. Now she’s in Gaza.”

Mia Schem was seized at a desert rave just over the border from Gaza that became the site of what is believed to be the worst civilian massacre in Israeli history. At least 260 people were gunned down as heavily armed militants in trucks and on motorcycles barreled through the vast field on Kibbutz Re’im where thousands had gathered for a carefree night of electronic music.

Civilians and soldiers, young and old, Israelis and non-Israelis were among at least 199 people taken into captivity from Re’im and other areas in southern Israel.

“This is a crime against humanity and we should all gather and stop this terror and bring everybody back home,” Keren Schem said. The United States (US) on Tuesday called on Hamas to immediately release all hostages, which include American citizens. “There should be no reason for them to have any hostages in the first place. And number two, we’re working very, very hard with our partners in the region to secure the release of all the hostages,” US National Security Council spokesperson John Kirby said on NBC’s “Today” show. “We know there’s a small number of Americans, but all of them need to come home and be with their families, and we’re working on that very, very hard.” The plight of the hostages has dominated Israel’s media since the attack. The seizure of so many civilian hostages is unprecedented in Israel’s history, and interviews with relatives are broadcast throughout the day.

The Israeli military said Schem’s family was told of her abduction last week, and officials dismissed the video as propaganda designed to make Hamas look humane. Israeli officials have vowed to maintain a siege on Gaza until the hostages are released.

Mia Schem has dual nationality with France, and on Tuesday, French President Emmanuel Macron decried the hostage-taking.

“To have taken hostages, both civilian and military, of all nationalities and to use blackmail at this time is absolutely odious and unacceptable,” Macron said at a news conference in Albania.

France, he added, was working with Israeli authorities and with Hamas through third parties to win the release of French and other hostages.