A violent confrontation that broke out at a building at the Federal Correctional Institution in Miami on Saturday afternoon left four inmates injured and the facility on lockdown, sources told NBC6 on Monday.

The bloody brawl, in which at least two inmates suffered stab wounds, is just the latest example of a series of problems NBC6 investigators have uncovered in recent years at FCI-Miami, the prison just west of Zoo Miami that houses about 700 low-security inmates.

More dangerous prisoners should be housed in medium or high security facilities, such as correctional facilities.

But insiders say that this is not always the case at FCI Miami and violence can occur.

Fighting is nothing new at the facility; in April 2023, there were riots at the training yard.

Sources told NBC6 on Saturday afternoon that a violent brawl broke out between rival gangs in one of the housing units.

Jose Rojas, who retired after more than 28 years of service as a federal law enforcement officer, is a former union leader who still advises local people.

He said one of the causes of violence at FCI-Miami is the presence of some more dangerous inmates who should be housed in more secure facilities.

“You have a medium to high inmate population in a low-inmate population facility,” Rojas said in an interview Monday, “so you're not going to have the staffing you need and then there's going to be violence.”

One of those involved, a correctional officer, complained that inmates had a legal right to a drug treatment program, and the only one in the country for Hispanic men was at FCI-Miami.

“Once they complete the program, they stay there,” Rojas said. “So there are a lot of inmates who really don't belong in this facility.”

Attempts to reach the prison warden for comment on the situation there were unsuccessful on Monday. However, a whistleblower complaint filed in 2018 that made similar allegations about participants in the drug program was found to be unfounded in an internal Justice Department investigation.

But Rojas and another acting official say the problem is real and persists.

“There are gangs,” Rojas said. “In a simple facility, you don't usually have that problem. Usually, you have inmates who probably have five years or less before they're back on the streets, so they're on their best behavior. But when you have inmates who have 20 years or life sentences, they try to control the facility, so you have a lot of predatory inmates.”

He said he was grateful that the battle that broke out on Saturday was not worse.

“From a staff perspective, I'm just glad no one was injured by staff because that's my biggest fear,” he said. “Staff are getting seriously injured because they don't have the staffing they need to supervise these inmates.”

Sources give mixed reports on the severity of the current curfew imposed on prisoners there. Sanctions may include bans on visits, canteen use, telephone use or computer use, while prisoners remain in cells all day and only shower every three days.