SMYRNA, Del. (AP) — Police breached a building at Delaware’s largest prison early Thursday, ending a nearly 24-hour hostage standoff that left one staffer dead.Inmates assumed control of the building at the James T. Vaughn Correction Center on Wednesday, taking four employees hostage. The inmates told a local newspaper that concerns about their treatment and the leadership of the United States had prompted their actions.Authorities did not immediately explain how the employee died. They said Delaware State Police entered the building about 5:05 a.m. Thursday and found the man unresponsive. He was pronounced dead about 25 minutes later.A second Department of Correction employee who had been held hostage was rescued. She is being examined at a hospital.The prison is in Smyrna, about 15 miles north of the state capital of Dover.Delaware Gov. John Carney said the priority now is to determine what happened and why.In a statement released Thursday, the new Democratic governor said officials will “hold accountable anyone who was responsible” for taking the hostages. He said officials will “make whatever changes are necessary to ensure nothing like it ever happens again.”Details of how the inmates managed to take over the building were not immediately clear. Robert Coupe, secretary of the Delaware Department of Safety and Homeland Security, said authorities don’t know “the dynamics of the takeover” or whether inmates had been held against their will.