In a major breach, a control panel at Miami’s Turner Guilford Knight jail malfunctioned, causing the electronically controlled cell doors to slide open in a maximum-security wing.

During the ensuing chaos, four inmates rushed into the cell of Kenneth Williams, attacking him.

The inmate saved himself by leaping off the second-floor tier, crashing to the floor below and severely injuring his ankle and back.

Miami-Dade corrections officers pepper-sprayed the attackers and confiscated at least two homemade shank. Williams, himself a reputed Liberty City gang member, was arrested for possession of a contraband blade.

The June 14 episode is another black eye for a Miami-Dade jail system long plagued by complaints of shoddy conditions and lax security. The episode, detailed in internal reports obtained by the Miami Herald, was the second time in recent weeks the newly installed security door system opened suddenly without warning.

The same thing happened May 20, although there were no incidents that time.

“I still can’t believe it actually occurred,” said Williams’ lawyer, J.C. Dugue. “The negligence is amazing, especially if they knew this was already a problem. My client has lots of enemies in jail and he is in a safety cell for a reason.”

In all, 48 cell doors opened for less than five minutes, said Marydell Guevara, assistant director of the Miami-Dade Corrections Department. The mishap is under investigation, she said

But the “group release” feature on the door system has been permanently disabled for the TGK maximum security wing known as K-81, where high-risk inmates are kept to protect themselves or others, she said.

The computerized sliding door system was part of an ongoing $1.4 million security upgrade at TGK, slated for completion next month.

The same sliding door system already has been installed at the MetroWest Detention Center, 13850 NW 41st St, at a price of $1 million. Both systems were installed by Black Creek Integrated Systems, which specializes in corrections security systems.

The upgrades were aimed at renovating Miami-Dade jails, which were the subject of a sweeping U.S. Department of Justice probe two years ago. The probe chronicled poor conditions at the jail system, one of the largest corrections systems in the country.

Miami-Dade grand juries have blasted deplorable conditions at county jails twice, in 2004 and 2008.

Most of the scrutiny had fallen on Miami-Dade’s aging Pretrial Detention Center. But TGK, about 10 miles west, has not escaped scandal.

In December 2005, a serial rapist shimmied down ropes fashioned from bed sheets and escaped. That prompted the creation of a task force that reported outdated facilities, poor training, slack security, too many job vacancies and a ballooning population of mentally ill inmates.

Investigators are looking at the computerized control panel that controls access to the sliding doors.

The panel features a group release button that, in TGK’s normal dorm-style housing units, allows for quick head counts of inmates. However, in a maximum-security, single-cell setting, the feature is not needed since inmates are not allowed to interact in a common area.

But on May 20, the group release feature was mysteriously activated. Officers on duty insisted no one pressed the button.

In response, technicians added an extra feature — the button now must be pressed twice, Guevara said.