In the span of three hours at a southwest Alabama prison, one inmate was fatally stabbed and another was seriously wounded after being stabbed in a separate fight.

Eighteen inmates have been killed by other inmates since October of 2016, according to statistics and news releases from the Department of Corrections.

The Montgomery-based nonprofit organization Equal Justice Initiative released a report last week finding that Alabama's prisons are the most lethal in the nation. The report found that Alabama's rate of over 34 homicides per 100,000 people incarcerated is more than 600 percent greater than the national average from 2001 to 2014.

Equal Justice Initiative attorney Charlotte Morrison said prison staff and inmates live "under constant threat of violence."

"The violence is epidemic," Morrison said. "We have a crisis that is not going to get better until we see a more effective and committed response from state leadership to addressing the issue

Bob Horton, a spokesman for the Department of Corrections, said the prison homicide rate is a "priority concern." He said he could not comment on the nonprofit's findings because he did not know how they did their comparison.

"There is a direct correlation between the level of prison violence and the shortage of correctional staff in an overpopulated prison system with limited resources for rehabilitating offenders. The proliferation of drugs and criminal activity inside prisons also contribute to an increase in violent incidents," Horton wrote in an email.

"The Alabama Department of Corrections recognizes the seriousness of the problem and is taking steps to reverse this trend," Horton wrote.

The prison system's monthly reports list that 16 inmates died in homicides in fiscal years 2017 and 2018. So far this fiscal year, the department has reported two fatal stabbings.

Twenty-nine-year-old Vaquerro Kinjuan Armstrong was fatally stabbed Dec. 2 at William C. Holman Correctional Facility in Atmore. Armstrong was serving a 22-year sentence on a 2009 first-degree robbery conviction in Talladega County. About three hours later, another inmate was critically wounded when another fight broke out in the same prison.

Staffing levels have been raised as an issue in an ongoing lawsuit over prison mental health care. Alabama Corrections Commissioner Jeff Dunn told The Associated Press earlier this year that estimates filed with the court show the state needs to add about 1,800 officers — nearly doubling current staffing levels.

The department has begun an effort to recruit and retain additional staff. As an initial effort to increase officer ranks, the department authorized a five and 10 percent pay increase for officers at minimum and maximum security prisons.

State Sen. Cam Ward, co-chair of the legislative prison oversight committee, said EJI's finding sounded accurate.

Ward said a side effect of sentencing reform efforts, which sought to relieve prison overcrowding by keeping nonviolent offenders out of prison, is that prison populations are made up mostly of violent offenders.

The Equal Justice Initiative filed a class-action lawsuit in 2014 against the state Department of Corrections in connection with previous homicides and assaults at St. Clair correctional facility.

The Equal Justice Initiative said it re-initiated its investigation of Elmore Correctional Facility this year after receiving dozens of reports of stabbings, assaults, extortion, and excessive use of force.