Tory Lanez allegedly opened fire on Megan Thee Stallion early Sunday morning after arguing with her and her friend ... according to sources directly connected to the investigation.
We're told the argument started after the group left a Hollywood Hills party together in the chauffeur-driven SUV, and at some point, Megan and her friend, Kelsey Nicole, wanted out of the vehicle.
Our sources say Tory opened fire from inside the vehicle, and allegedly hit Meg in the feet twice. TMZ broke the story ... LAPD pulled over Tory's ride a short time later. Megan's feet were clearly bleeding on the sidewalk as she followed police instructions to exit the vehicle.
Tory was arrested for possession of a concealed weapon. As for why he hasn't been booked for the alleged shooting?
Well, sources connected to Tory say there are mitigating circumstances. Based on what we know, we believe he's going to say it was an accidental shooting.
Also, the initial report to cops was someone had fired a gun into the air, not at someone. Megan initially told police she had cut her feet on glass, but remember ... she's the victim in this case -- as police had listed her from the start. It's entirely possible she felt intimidated as an alleged domestic violence victim.
There's also this complication -- witnesses are not cooperating with police up to this point, according to law enforcement sources ... and without witnesses who are willing to testify it might be hard to prove the case against Tory.
However, we're told police have been notified that there is cell phone video of the shooting. Our law enforcement sources tell us they have not put eyes on that video yet -- again, witnesses have been difficult -- but, obviously, if they do see it ... it could dramatically change the case.