TECUMSEH, Neb. — A weekend revolt at a Nebraska maximum security prison that saw inmates temporarily take control of half the housing units left two prisoners dead, authorities said Monday, probably killed by other inmates.

Four other prisoners were injured and two staff members were assaulted at Tecumseh State Correctional Institution about 60 miles southwest of Lincoln, which houses serious offenders including Nebraska’s 11 Death Row inmates.

Corrections Director Scott Frakes said the disturbance began around 2:30 p.m. Sunday when about 40 inmates gathered in front of a housing unit. The two prison staffers were attacked when they tried to break up the gathering.

“As the group of inmates became more volatile, staff members were unable to control them,” Frakes said at a news conference Monday.

Frakes described a harrowing, 11-hour ordeal, during which 100 to 200 of the roughly 1,000 inmates at the prison participated in the revolt.

They took control of two of the four housing units, broke windows, tore down a wall dividing the housing units and removed security cameras, he said.

Some prison staff barricaded themselves in offices, Frakes said.

Smoke rose from the two housing units Sunday, and driveways to the prison were blocked.

“We didn’t know if the inmates had acquired weapons during this time, in some cases they had destroyed or covered the cameras, so we didn’t have a good sense of what was on the other side of the door until we opened it,” Frakes said.

The housing units sustained fire, smoke and water damage.

Frakes said the prison was finally secured by 1 a.m. Monday.