NBA's Allen Crabbe Saves L.A. High School With Huge Donation

Allen Crabbe is a new hero in L.A. ... 'cause the NBA star just forked over enough cash to save an entire high school!!

Frederick K.C. Price III Christian School in south Los Angeles was set to shut its doors for good this week after it lost the backing from a local church -- until the Brooklyn Nets star caught wind of it.

Crabbe -- who attended the prestigious inner-city school from the time he was in diapers to when he graduated some 18 years later -- agreed to supply the funding to keep the school ticking.

Unclear how much he actually kicked in for the cause ... but sources tell TMZ Sports it was a substantial 6-figure check.

“I was at that school practically my whole life,” Allen says. “I’m just happy and feel blessed to be in a position now to do this.”

Thanks to Crabbe ... 175 kids don't have to find a new school next year -- and school officials are calling it a "miracle."