Los Lonely Boys Singer -- Hospitalized After Falling Off Stage

The lead singer of Los Lonely Boys -- the band responsible for the hit 2003 song "Heaven" -- is currently holed up in an L.A. hospital ... after taking a nasty fall off stage following a concert last night.

According to the band's rep, the Boys had just finished their set when singer Henry Garza tried to greet some fans, but misjudged his step and toppled off the stage ... falling right into the orchestra pit.

We're told Henry's bandmate and brother, Joey Garza, immediately jumped down to his aid ... and Henry was transported to a local hospital.

The band was forced to cancel three performances in Hawaii this weekend as a result of the fall.

According to the rep, Henry's expected to recover just fine -- it appears there was no long-term damage done. It's currently unclear when the band will go back on the road.