Six staff members at Union Correctional Institution are on administrative leave during an investigation of criminal activity.
The nature of the allegations were not disclosed, but Department of Corrections Secretary Michael Crews said there was "alleged criminal activity that compromised the safety of both staff and inmates."
The Florida DOC said it has zero tolerance for illegal, inappropriate and unbecoming behavior by officers and staff.
"This type of behavior is a distraction from our primary mission of public safety and cannot be allowed to dishonor the reputations of thousands of hardworking officers who daily go in harm’s way to ensure the safety of Florida families," Crews said.
The DOC said it will not discuss the case until the investigation is complete. It hasn't said if what happened involved inmates.
"I've got quite a few friends and relatives out there. Nobody has said anything," resident John Dowling said.
"I always thought it was a pretty good prison, well-established and everything," a resident named Loretta said. "The security was great, in my opinion. I just don't know what this lockdown is all about."
This is the second problem reported at a northeast Florida prison in just three weeks. Last month, several agencies investigated a shooting at the Columbia Correctional Institution in Lake City that left two inmates injured.
State Sen. Charles Dean Sr., whose district includes Union and Columbia counties, declined to comment about the ongoing investigation.
Those who live in the area want to know what happened, and they want answers soon.
"If it's a safety issue, they need to come out with it and let the public know," Dowling said. "If it's something internal, something inside the prison, I think the public should still know about it."
The department has not said how long the investigation will take.