Yoav Shimoni opened up to ABC News about the traumatic moment he saw a graphic video of his beloved grandmother lying on the floor of her home dying, surrounded by Hamas terrorists who posted her final moments on her Facebook for her family to see.

Just 10 minutes before militants broke into Bracha Levinson's home on Saturday at Israel's Nir Oz kibbutz, Levinson was texting her daughters, "concerned about them more than she was herself," said Shimoni, 24, who lives in Canada.

But then Shimoni's sister frantically messaged the family text group asking if they had seen their grandmother's Facebook post.

"Immediately, I went to her Facebook page. And I saw a video with her lying on her living room floor with her arms clenched on her chest, covered in blood, and blood surrounding her. A few men with guns standing above her and shouting," Shimoni said.

"We all saw the video. Even my little brother," he said.

"I was freaking out, trying to make sense of what's happening. Just, like, pacing around my condo," he said. "I'm trying to call my parents, and hearing my mom screaming her lungs out to the phone when my dad is trying to, like, calm me down and try to explain to me what is happening."

The 24-year-old was in shock, he said, and also scared for the rest of his family who live in Israel.

As the day went on, Shimoni said, the family learned that not only did the militants take Levinson's and post "her dying body for us to see, but they also burned down her house and the entire community which my mom grew up in, I spent most of my summers in."

Levinson, 74, lived in Israel since she was a child after the Holocaust. She raised her children as a single mother in the Nir Oz kibbutz, where she lived the rest of her life. She was known in the community for the bicycle she always rode around as her main transportation.

"She was truly the pillar of our family, and a pillar in her community," her grandson said.

Shimoni last saw his grandmother at her home two weeks ago for the Jewish high holidays. Levinson always felt safest at her home, he said.

"There was no sense of any danger there," he noted. "Coming from the outside to that region, always you feel a bit tense, but it's always the thought of like 'OK, if there's a missile or something, then go to the shelter and we'll be safe.' Which, unfortunately on Saturday, that wasn't the case."

Shimoni said he wants his grandmother to be remembered for her love of her family and her kibbutz.

He said he's comforted knowing his grandmother didn't have to witness "her community being torn apart."

And Shimoni said his heart breaks for everyone whose loved ones were taken hostage.

"At least I know that my grandmother is not suffering anymore," he said. "I imagine the pain that the neighbors, my mom's colleagues, and my family's friends, and all my friends are experiencing right now, with the unknowing of what happens with their loved ones that are in Gaza."