The Oakland Police Department is looking into a viral video that allegedly shows the shooting that ended reality star Kash's life.

OPD confirmed they're looking into the clip, which is making the rounds online ... telling us it has been forwarded to the case investigator for review.

The video is graphic ... it shows a fight breaking out between two women -- with the pair trading blows and pulling hair -- when a third woman runs up and starts smacking down at one of them.

This third woman appears to be holding something in her hand when she runs up and starts swinging -- when suddenly the fight stops, people scamper off, and the woman on the ground lies completely still.

We're told the OPD cannot verify the video as of yet.

As we reported ... cops have charged Vernika Dunbar -- Kash's sister -- with involuntary manslaughter in connection with her death, claiming Vernika accidentally shot her sis when her gun went off while she was attempting to pistol-whip the other woman.

Kash was rushed to the hospital, where she was pronounced dead.