Two inmates have been killed during a disturbance at Tecumseh State Correctional Institution in southeast Nebraska.
No details have been released about how the inmates died.
The prison was placed on lockdown for roughly three hours on Thursday after inmates in a housing unit refused to return to their cells and a fire was started in a courtyard.
Officials say about 40 inmates in a unit with 128 prisoners were involved.
Prison spokeswoman Dawn-Renee Smith says the lockdown began around 2:45 p.m. and lasted until about 5:30 p.m.
No prison employees were injured.
In a statement posted on Facebook, Gov. Pete Ricketts said the incident was "swiftly resolved and public safety was never at risk."
The Associated Press reports:
"The incident took place at the same housing unit where two other inmates were killed during a May 2015 riot that caused roughly $2 million in damage.
"That riot, which also left several staff members injured, involved several hundred inmates in three living units, a gym and a courtyard.
"An investigation later found that prisoners were trying to air grievances about what they viewed as perks given to certain inmates and not others and disrespect by inexperienced staff members."
Ricketts also said that those responsible for the "loss of life will be prosecuted to the full extent of the law."