Fetty Wap's Crew Fired First, Only Their Shots Landed in Shootout

Fetty Wap's crew fired off the only bullets that landed in the shootout after he was robbed -- including a possible self-inflicted gunshot wound ... TMZ has learned.

Eyewitnesses at the scene tell us a member of Fetty's crew fired first at Raheem Thomas' crew in retaliation Sunday morning ... and then that same person allegedly accidentally shot himself in the thigh.

We're told the shooting started after Fuzz and his Muscle Team boys followed Fetty and co. into a Paterson, NJ deli, where things got violent fast. Sources say Fuzz pistol whipped someone in Fetty's camp, and then he and his guys robbed Fetty and his crew on the spot.

That's when a second gun was taken out and shots were fired back and forth ... 2 of which landed on 2 of Raheem's guys. At some point after the initial bloodbath ... we're told the original shooter tried escaping and the gun fired in his waistband, striking him in the thigh.

That account roughly matches up with what cops have told us. As we reported ... 2 men were found in the immediate area of the shootout and were transported to hospitals. A 3rd guy thought to be involved checked himself into another hospital soon after.

Raheem's already been booked for gun possession and assault after showing off Fetty's stolen chain on social media -- but it's unclear if he actually fired in the gun battle, despite being seen with a firearm. Prosecutors in court Monday said they did not believe Raheem had personally fired.