An off-duty British-Israeli soldier threw back seven Hamas grenades targeted at a shelter by gunmen during the attack on a music festival on 7 October, Sky News has been told.
Aner Shapiro was killed when the eighth grenade thrown at him went off in his hand as he heroically attempted to defend his fellow festival goers.
His grandmother Yamima Ben-Menahem told Sky News how he valiantly stood up against the militants and did his best to keep people calm.
She said: "They were trying to get out of the party and then there were alarms and there were missiles.
"And they went into a shelter he was with his friend Hersh Goldberg but there were about 30 other people there.
"First of all he calmed them down saying the army was only half an hour away and he was sure everything was going to be okay.
"He was a natural leader, wherever he was."
She went on to say how Hamas approached the shelter he and others were hiding in and started flinging hand grenades into it.
"When the terrorists came nearer, he stood at the entrance, and when they started throwing grenades into the shelter, he said 'I'm going to throw them back', and if I miss one, you do the rest of the work.
"He just stood there and threw back one grenade after the other.
"From what his friends told us he managed to throw back about seven grenades, and then the last one exploded in his hands."
The grieving grandmother said it took the family three days to learn of his valiant, but ultimately fatal stand.
"The people who survived started calling us after they found out who his family was and one after the other said 'he saved our lives'," she said.
Ms Ben-Menahem added that after he died, Hamas went back in and took five or six hostages before opening fire on those who remained.
It took hours before help arrived, meaning only those who had suffered relatively minor injuries survived, she said.
Describing her grandson, she said: "He was handsome, good-natured, gifted in all kinds of areas, he painted very well and he played the piano."
Ms Ben-Menahem added that she hoped Aner's friend, Hersh Goldberg, who was apparently taken hostage, will be returned safely.