Alijah Arenas Car Crash Video Shows Fiery Wreck, Star Writhing On Ground

Basketball phenom Alijah Arenas rolled on the ground in a huge puddle of water just moments after he was ripped from a burning Tesla Cybertruck ... video, obtained by TMZ Sports, shows.

The clip was recorded by a neighbor who tells us he heard the crash happen at around 5 AM Thursday just outside of his home in L.A.'s San Fernando Valley.

The witness says he raced out and saw Arenas stuck inside the flame-engulfed vehicle after it had barreled over a fire hydrant and come to a stop on a nearby tree.

Alijah -- who we're told was shirtless and shoeless by the time Good Samaritans reached him -- was pulled from the ride and placed on the road, just a few yards away from the accident. You can see him rolling around in apparent pain ... all while clearly trying to catch his breath.

The witness said moments later, the 18-year-old high school basketball phenom was placed on a stretcher and taken to a nearby hospital.

Authorities stated Thursday he was transported in "stable condition," though no further medical update was given.

Alijah, the son of former NBA superstar Gilbert Arenas, is a five-star recruit who committed to USC earlier this year. He averaged 31 points and 7.8 rebounds ... and was so impressive, he told us earlier this month, adidas had actually inked him to a sponsorship deal.