Larry Nassar, the disgraced former sports doctor convicted of sexually abusing female gymnasts, was reportedly stabbed multiple times during a spat with a fellow inmate at a Florida federal prison.

Nassar, 59, was stabbed twice in the back, twice in the neck and six times in the chest on Sunday, Joe Rojas, president of Local 506 — a labor union representing employees at the Federal Correctional Complex, Coleman in central Florida — told NBC News.

He was also reported to have suffered a collapsed lung, but is in stable condition, said Rojas, who confirmed the details with on-duty staff.

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According to the Associated Press, which cited sources familiar with the matter, the attack happened at United States Penitentiary Coleman, which is part of the correctional complex, and where officers assigned to Nassar’s unit were working overtime shifts.

One of the officers was on a third straight shift, working a 16-hour day and another officer was on their second straight shift, the anonymous sources said, adding that the prison was experiencing short staffing.

The Federal Bureau of Prisons told NBC News that Nassar was assaulted by an unnamed inmate around 2:35 p.m. Sunday. Nassar received life-saving measures and was taken to a local hospital.

“No staff or other inmates were injured and at no time was the public in danger,” officials said, adding that the investigation is ongoing.

The sports doctor was sentenced to decades in prison after being convicted in both state and federal courts for sexually assaulting gymnasts, including Olympic medalists, such as Simone Biles.

Nassar worked at Michigan State University and at Indianapolis-based USA Gymnastics, working with training Olympians. He separately pleaded guilty to child porn possession, the AP reported.

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Several athletes testified in 2018 that Nassar’s decades-long sexual abuse went unreported, even after telling coaches and trainers.  

In July 2021, the FBI was accused of failing to stop Nassar’s abuse when made aware of the situation. More than 40 girls and woman said they were molested during the time the FBI knew of the allegations against the sports doctor, according to the AP.

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The Michigan Supreme Court rejected Nassar’s final appeal in June 2022, when attorneys said their client was treated unfairly and deserved a new hearing. The appeal was based on the judge’s remarks, including calling Nassar a “monster” who would “wither” in prison like the wicked witch in The Wizard of Oz, according to the AP.

“I just signed your death warrant,” Ingham County Judge Rosemarie Aquilina said after sentencing Nassar.

Nassar has been held at Coleman since 2018 in a unit with other sex offenders, Rojas told NBC News.

“It’s unusual that this would happen in that unit,” Rojas added.

An Associated Press investigation in 2021 revealed that correctional officer position vacancies have left prisons to use cooks, teachers, nurses and other workers to guard inmates to the detriment of security and safety.

“This is why it happened,” Rojas said of the stabbing. “We don’t have the staff.”