LINCOLN, Neb. (AP) — Officials say a deadly uprising at a Nebraska prison began because inmates were angry that prison staffers had confiscated 150 pounds (68 kilograms) of homemade alcohol from them.

Corrections officials said Thursday that the inmates made the alcohol using bread, fruit and sugar from the prison’s kitchen and stored it in watertight footlockers under their beds.

Officials say inmates also were angry about what they perceived as a correctional officer’s assault on a prisoner at the Tecumseh State Correctional Institution. Warden Brad Hansen says security footage shows the officer bumped into the inmate unintentionally on a narrow walkway.

Hansen says both incidents contributed to the March 2 uprising that left two inmates dead.

Corrections director Scott Frakes says officials have made improvements in response to an outside consultant’s review.