Meek Mill -- Pistol-Whipping Goes Down On Rival Rapper's Crew (VIDEO)

Meek Mill's beef with a rival exploded into a pistol-whipping melee on the streets of Philly ... with people fleeing for their lives -- and the violence is crystal clear in this video.

Meek and his crew were shooting a music video Tuesday evening ... when Louie V Gutta and his homies showed up. Watch the video -- there's a little bit of jawing, a little bit of pushing, tensions rising, and then ... chaos.

A guy standing behind Louie V got CRACKED in the face with what looks like the butt of a handgun -- and then everyone scatters ... fearing a shootout was about to go down.

No shots were fired, but police were called to the scene. No one got arrested.

Right after the incident, Louie V claimed he wasn't involved but admitted he was there talking to Meek.