Louis Tovar's mother, Blanca Ismeralda Tamayo, is the only surviving victim of the horrific shooting rampage.
Tovar said she is relatively unresponsive at the moment but he's holding out hope that she'll recover.
"I need her in my life, especially after losing my dad, my sister and my little brother," he said.
WATCH: Louis Tovar's interview with our sister station KABC-TV
Staying focused on his mother's recovery is giving Tovar hope as he grieves.
The shooting happened at his father's business on Wednesday. The gunman killed four people: Luis Tovar Sr., his daughter Genevive Raygoza, Leticia Solis Guzman and Louis' 9-year-old brother, Matthew Farias.
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"(He was) the most loving brother anybody could ever ask for. He would always be jumping on me, my sister, my mom. I can hear him telling me, 'oh I love you, brother' and he was nine years old and he was still like that," he said.
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Tovar said his mother needs more surgery and will require long-term medical treatment and care.
"My mom knows I need her and when she heals, she's going to need me," he said.
A GoFundMe account has been set up to help the family pay for her medical expenses.
Other GoFundMe pages were established to help the other victims' families:
- GoFundMe to help family of Matthew Farias
- GoFundMe to help family of all of the victims
- GoFundMe to help family of Genevieve Raygoza
- GoFundMe to help family of Leticia Solis Guzman
Although investigators said the shooting was not random, a motive remains unclear. The suspected gunman, who authorities say knew all the victims, has been charged with murder.
The video in the media player above was used in a previous report.