Hundreds mourned a rising basketball star who died of a rare form of cancer Thursday, a day before he was set to graduate from his Redondo Beach high school.

Ryse Williams, 18, played basketball at Redondo Union High School and was set to join the team in the fall at Loyola Marymount University, where he also received a full ride scholarship. He was supposed to go to orientation this weekend.

"He was a star, but he didn't act like it," his high school principal, Jens Brandt, told NBC4 at a vigil in Williams' hometown of Corona. "That was Ryse. He was an exceptional young man."

Williams started feeling sick weeks ago. He later found out he had stage four renal medullary carcinoma, a rare and aggressive form of cancer that affects the kidney. He died Thursday morning.

"He was stricken with an ugly, nasty cancer," his father, O'Brey Williams, said. "Once you're diagnosed with it, it's too late."

One of Williams' best friends drove five hours to grieve with the hundreds who at the candlelight vigil at the court where he grew up playing basketball.

"I'm just trying my hardest to stay as strong as I can," Elijah Nesbit said tearfully. "I know Ryse is looking down on us right now. I just want to say, 'I love you, man.'"

Redondo Union High School will honor Williams by playing his jersey on an empty chair at Friday's graduation ceremony.

"Right now, I'm looking out to all of you guys. I just can't help but be happy," said his sister, Sierra Williams, as she adressed the crowd Thursday. "He got to live 18 full years of a life of love from all of you."

