He thought his daughter was killed by Hamas. Now he's 'back in the nightmare' of knowing she's a hostage.

For more than three weeks, Tom Hand thought his 8-year-old daughter, Emily, was dead following Hamas' surprise terrorist attack on Israel. Given the alternative, he said he was "relieved."

Emily was staying at a friend's house in Kibbutz Be'eri the night of Oct. 6 and was there when the attacks of Oct. 7 began, Hand told ABC News. Dozens were killed there as Hamas terrorists went house to house, slaughtering unexpected civilians shocked at an unprecedented invasion of their quiet community.

For days after the gunfire died down, Hand didn't know where his daughter was. However, on the Tuesday after the attack, elders in his community brought him to a meeting and told him she was one of the hundreds killed as Hamas invaded kibbutz after kibbutz, slaughtering civilians in their rampage.

"How sure are you?" he asked them. "95%," he said they told him. "That was good enough for me," Hand said.

But officials never found her body. Hand said there was no blood in the house where she was that morning, no blood outside in the driveway or in the yard either.

But still, Hand and his family were convinced she was dead.

"Totally believed that she was dead and sort of relieved because it would've been quick -- quick and fast," he told ABC News in the hotel room where he's been staying since evacuating his old neighborhood. "She wasn't suffering or going through any trauma or being terrorized, it was like okay, I can deal with that."

Until last week.

That's when he said government officials told him the information he'd received was wrong. They said they now believe Emily was taken alive to Gaza, held hostage by Hamas, based on a lack of evidence proving her death.

"It was either you're dead or they've taken you," Hand said.

"Now, I'm back in the nightmare," Hand said. "I don't know how they've taken her, dragged her, pushed her along, screaming at her, shouting at her. I don't know how terrified she is just being taken away. Being taken out of the kibbutz, taken to Gaza, down into the tunnels of Gaza, that's a creepy, scary place. I'm imagining all her terror along the way."

So now he said he waits and prays every day along with his two older children from another marriage and the hundreds of other hostage families in similar positions. Emily's mother, Liat, died of breast cancer when she was still young.

To her captors, Hand said he has a message.

"Show the world that you have got humanity, that you have got pity, you have got mercy, at least let the children and the babies come home," he said.

And to his daughter, another.

"You will survive it. And we'll get you home and never let you out of our sights again."

Emily Hand will turn 9 on Nov. 17.

There are still at least 240 Israelis being held hostage by Hamas, according to the Israel Defense Forces.

In Israel, at least 1,400 people have been killed and 6,900 others have been injured since Oct. 7, according to Israeli officials. In the neighboring Gaza Strip, at least 10,328 people have been killed and 25,956 have been injured, according to the Hamas-run Gaza Health Ministry. Those numbers have not been independently verified.