CHULA VISTA, Calif. (KGTV) – A mother is appealing for information after her teenage son was stabbed to death at a Chula Vista house party.

“I’m heartbroken. There’s no words for the feeling. I can’t describe it,” said a tearful Sam Castillo.

For Castillo, a mother reeling in grief, the last few days have been surreal.

“Definitely a nightmare I wanted to wake up from,” said Castillo.

Castillo, who lives in Seattle, says on Friday night, her ex-husband agreed to let their son Mateo, 17, go to a birthday party if he took his brother, Jesus, 15. A friend picked them up around 6 p.m. at their El Cajon home. Castillo says according to Jesus, the party at a home on Rigley Street in Chula Vista was uneventful until just before 1 a.m.

“It was good vibe kind of party,” said Castillo. “Jesus was inside the house. He said he did hear, ‘Fight, fight, fight!’ And then he said he looked out the window and saw his brother walking into the house, hunched over and holding his stomach, so he ran to him.”

Mateo had been stabbed. Jesus and several others tried to apply pressure to Mateo’s wound. Paramedics later pronounced him dead.

“It’s my only consolation that my son didn’t die alone,” said Castillo.

Mateo’s brother, Jesus, was inconsolable.

“He’s devastated. First thing he told me was, ‘Mom, I’m sorry I couldn’t do more,’” said Castillo. “Mateo was such a sweet kid, always smiling and always happy. Always making others laugh.”

A fixture in the weight room, Mateo, a senior at Vahalla High, planned on enlisting in the Marine Corps.

Instead, that promising young life was cut short. A mother is now appealing for tips to find her son’s killer.

“It’s not fair for him. For to have suffered that … Help us find and get justice for my baby,” said Castillo.

A Gofundme campaign has been set up to help the family with funeral and other expenses.

Two other teens were also injured at the party. At last check, they were both in stable condition.

Anyone with information on the case is asked to call Crime Stoppers at 888-580-8477.