There were no discernible voices, but there was an unmistakable message written on everyone's lips and in everyone's eyes - this wasn't supposed to happen.
Katz, 26, along with Liz Trubeshi, 17, were killed Saturday by an unidentified gunman at a gay and lesbian youth center in Tel Aviv.
"I'm wearing this flag today because this is where it all starts," Chen Katz, Nir Katz's sister, said in her eulogy while wearing a gay pride flag. "The struggle begins here, here is the source - what did Nir do? Nothing against anybody."
It is the second tragedy to strike the Katz family. Katz's father, Rami, was one of five soldiers killed in a training accident in Tze'elim in 1990, when Nir was seven years old.
"I think that the message of my life is over," Ayala Katz said in her eulogy.
Café Noir, where the shooting took place, is a popular hangout for Israel's homosexual youth. It provided an environment for interaction, and many did not make their sexual orientation public knowledge outside of that circle of friends.
Katz was a counselor at the center for several years and helped teenagers embrace their sexual identity.
"He was not the typical gay stereotype," said Re'em Gefen, 21, from Tel Aviv, who was friends with Katz for about five years. "He was not even a human stereotype or an Israeli stereotype. He was a person who volunteered. He had a purpose in life. I don't think I know anyone who has a purpose here and he just did."
Shir Sela, 16, from Ramat Gan, called Katz to see if he wanted to hang out at Café Noir just minutes before news stations televised information about the shooting. When she heard what happened, Sela called Katz's phone repeatedly.
"I felt broken and useless that I wasn't there to help him," she said. "Nir was the most special guy that I ever met before. He took care of everyone… he just kept everybody safe."
But hardly anybody in the gay community feels safe after Saturday's shooting, as one day has changed an entire city's social landscape. Tel Aviv, which has the highest population of homosexuals in Israel, has lost its aura of refuge for the gay community, people said.
"It was shocking, absolutely shocking," said Yogev Levy, 18, from Haifa. "It's supposed to be the open city, the safe city, the safe place. Especially in a place like that, this should never happen. It's appalling, it's very surprising, it's very sad."
Sela said she was sizing up every person at Monday's funeral, attended by some 400 people, looking for the unnamed assailant based on police report descriptions. Gefen said he didn't know whether he should even sit outside with friends, as he felt harsh gazes when he and a group of people marched down the street in shirts with the gay pride flag to honor Katz.
"It's as if we were going with the gay pride flag as a target on there," Gefen said. "It was like asking everyone to shoot us. It's Tel Aviv and nobody feels safe."
Sarah Ramler contributed to this report.