Milan — Christian Maire, the mastermind of an international child exploitation ring, was killed and a second defendant injured in what is believed to be a targeted stabbing attack by fellow inmates at Milan federal prison, sources told The News.

Maire, 40, of Binghamton, New York, the well-educated co-founder of a computer graphics company, died Wednesday night in an attack that left three others injured, according to Milan prison spokesman Dan Clore. One of the injured inmates is Michal Figura, 36, an IT specialist at the University of Pennsylvania, two sources familiar with the attack told The News.

The prison attack happened about 50 miles southwest of Detroit almost exactly one month after Maire, Figura and other members of a sex ring that hunted and manipulated children into performing sex acts online, were sentenced to decades in federal prison.

Details surrounding the attack that left two others injured were unclear Friday but one source familiar with the investigation said at least one attacker was armed with a shiv, or homemade knife.

“It’s a horrible tragedy and it seems something like this should have been able to be avoided,” Maire’s lawyer Mark Kriger said Friday.

Figura's lawyer declined comment Friday.

Clore said the altercation involved seven prisoners and took place in a housing unit. He said staff immediately responded to the area and separated the inmates.

The prison houses approximately 1,370 inmates.

In addition to the injured inmates, two staff members sustained minor injuries trying to break up the fight, officials said.

Clore said the Federal Bureau of Investigation is looking into the incident and treating it as a homicide.

Maire, who was less than one month into a 40-year prison sentence, died at an undisclosed hospital several hours after the incident, Clore said.

Maire and other members of the sex ring were confronted by victims during the sentencing last month. One 20-year-old victim was satisfied with Maire's 40-year sentence.

"That's basically life," the victim told The News last month. "And he's gonna get the hell beat out of him."

Members of the sex ring posted as teenage boys on social media websites to lure preteen and teenage girls to a private online chatroom, where more than 100 victims where manipulated into stripping, masturbating and performing other sex acts.

According to prosecutors, Maire handpicked members of the ring, known as the "Bored Group," who shared computer skills and a sexual interest in girls ranging from infants to teens.

Maire sobbed during his sentencing in federal court in Detroit as some of his victims recounted the emotional devastation his crimes caused.

"I've shattered so many lives," Maire told U.S. District Judge Stephen Murphy. "I never thought I could sink this low. I apologize to all of my victims. I took advantage of your youth and trust and put my own selfishness above your dignity."

At least five other members of the sex ring are incarcerated at Milan, according to prison records, and the attack has raised concern for their safety.

“It’s murder and it’s horrible for anyone to get hurt or injured,” said attorney Raymond Cassar, whose client Jonathan Negroni Rodriguez, 37, of West Hollywood, California, was sentenced to 35 years in prison and is currently being held in Milan. “This just doesn’t happen in a Michigan federal prison system.”

The attack illustrates the danger faced by pedophiles and perpetrators of sex crimes behind bars.

In late May, Larry Nassar, a former sports doctor at Michigan State University and USA Gymnastics who was convicted of sexually assaulting girls during medical treatment, was assaulted by fellow inmates at a high-security federal prison in Arizona. He was subsequently transferred to a prison in Florida.

Sarah Rahal and the Associated Press contributed.