H.S. Basketball Star Caleb White Dead At 17 After Collapsing During Workout

Caleb White -- one of the best high school basketball players in the country -- has tragically died ... after his family said he collapsed during an on-court workout at school on Thursday.

White's grandfather, George Varnadoe Jr., announced the sad news in a series of Facebook posts ... saying following the medical emergency, despite the best efforts of first responders at White's Pinson Valley High School and doctors at a nearby hospital, the point guard was pronounced dead.

He was just 17 years old.

"Our whole family was really looking forward to his upcoming senior season and afterwards, playing for a D-1 school and then perhaps the NBA," Varnadoe Jr. wrote in one of the social media posts.

"But......it wasn't meant to be."

The Alabama High School Athletic Association said in a statement Thursday evening it'd be providing grieving students and staffers with counseling in the upcoming days.

White -- a first-team all-state selection as a junior -- averaged 20.9 points, 3.8 rebounds and 3.1 assists per game last season ... and according to ESPN, he was the No. 3-ranked prospect in the entire state of Alabama.

Varnadoe Jr., though, said White was so much more than a hooper ... calling the teenager "an honor student, very respectful, high intellect" and an "excellent role model."

"RIP Caleb!" Varnadoe Jr. added. "I love you man!!!!"