PONTIAC, Mich. (WFLA/AP) — A man who went by the name “Boopac Shakur” and posed as a 15-year-old girl online to expose alleged sexual predators was fatally shot during an argument on Friday at a restaurant in Michigan.

The Oakland County Sheriff’s Office says two males were arrested after Friday night’s slaying of Robert Wayne Lee in Pontiac. Lee had gone by the name “Boopac Shakur” on social media.

Pontiac is about 25 miles northwest of Detroit.

Authorities say Lee confronted an 18-year-old and a 17-year-old in a restaurant.

Lee reportedly punched one of the two people, who pulled out a knife, according to NBC affiliate WDIV in Detroit. The other person pulled out a gun.

It’s unclear if the shooting was related to Lee’s efforts to identify sexual predators.

The sheriff’s office says Lee’s crusade had led to charges against several men — including a jail deputy, but his work also misidentified one person as a sexual predator.

“While we certainly understand his desire to hold child predators accountable, many times well-intentioned individuals who engaged in this don’t know the standard of evidence required for convictions and often underestimate the potential violence confronting a suspected predator,” Sheriff Michael Bouchard said to WDIV.

The Associated Press contributed to this report.