A gang-related dispute sparked an overnight riot in a South Carolina prison that killed seven inmates, the deadliest U.S. prison riot since 1993, state officials and prison safety experts said on Monday.

Another 17 people were wounded in an eight-hour long series of fights that spread through three dorms at the Lee Correctional Institution in Bishopville, South Carolina, said Bryan Stirling, director of the state Department of Corrections.

Stirling said that the fight centered on gang territory, contraband and cellphones in the jail.

'This was all about territory. This was about contraband, this was about cellphones,' Stirling told a news conference. 'These folks are fighting over real money and real territory while they are incarcerated.'

WARNING: GRAPHIC VIDEO

Seven inmates were killed and 17 injured after fights broke out at the Lee Correctional Institution in South Carolina at 7:15pm Sunday night. Above, a view inside the prison after the bloodbath

One inmate said that the fights were started by gang tensions

Pictured above is the inmate who posted the disturbing footage

THE SEVEN INMATES KILLED IN SOUTH CAROLINA PRISON RIOT LEFT: RAYMOND ANGELO SCOTT, 28 Incarcerated in July 2016 and sentenced to 25 years for charges of assault and battery, carrying a prohibited weapon and an additional weapons charge. Sentenced to 25 years in prison. RIGHT: EDDIE CASEY JAY GASKINS, 32 Incarcerated in December 2017 and sentenced to 10 years for domestic violence charges LEFT: MICHAEL MILLEDGE, 44 Incarcerated in April 2010 and sentenced to 66 years for charges of assault and battery, illegal drug possession, possession of narcotics trafficking in crack cocaine and additional firearm charges. RIGHT: JOSHUA SVWIN JENKINS, 33 Incarcerated in December 2015 and sentenced to 35 years for charges of burglary, voluntary manslaughter and attempted murder LEFT: DAMONTE MARQUEZ RIVERA, 24 Incarcerated in November 2015 and sentenced to life in prison for charges of murder, armed robbery, burglary and kidnapping. RIGHT: COREY SCOTT, 38 Incarcerated in October 2002 and sentenced to 87 years for charges of assault and battery, criminal conspiracy, carjacking, aggravated assault and battery, kidnapping and armed robbery CORENELIUS QUANTRAL MCCLARY, 33 Incarcerated in July 2011 and sentenced to 42 years for assault and battery, burglary, criminal conspiracy and firearms charges Advertisement

Officials said they would be working with the FCC and cellphone companies to block the cellphone signal in the prisons.

'Jamming those cell phone signals will do a lot,' Gov. Henry McMaster said. 'It's an absolute outrage that that is the law ... and we're doing our best to see that FCC law is changed and changed as quick as possible.'

It was the deadliest U.S. prison riot since 1993, when nine inmates and one corrections officer died at the Southern Ohio Correctional Facility in Lucasville, said Steve Martin, a prisons expert and now the federal monitor for the consent decree involving New York City's Rikers Island jail complex.

All seven deaths were the result of stabbing injuries, said Lee County Coroner Larry Logan.

Forty-four guards were on duty at the 1,583-inmate prison when violence erupted Sunday evening, Stirling said. Prison staff called in reinforcements and did not move into the first unit until four hours after the fighting began, a delay that he said was necessary to ensure the guards' safety.

One prisoner who saw the riot exchanged messages with the AP on the condition of anonymity because he is not allowed to have a cellphone and fears retribution from other inmates.

He says most of the inmates are affiliated with gangs and several attackers taunted a rival gang member who was hurt.

He said he saw bodies stacking up on each other and correctional officers didn't do anything to stop the violence or check on the injured.

About seven fights broke out just after 7pm on Sunday. It comes less than a month after an officer was briefly held hostage at the facility. Above, emergency crews on the scene overnight

The prison, which houses some of the state's most violent offenders, was secured around 3am Monday morning. Above, emergency crews at the scene

For months, South Carolina officials have said that prisoners used smuggled cellphones to manage crimes outside the prisons. Gov McMaster on Monday said he would renew his request to federal officials to allow him to block cell signals on prison property.

The State newspaper showed video it said was taken by inmates with smuggled phones that depicted trails of blood and dead bodies in the prison. Reuters could not immediately confirm that the video was authentic and Stirling declined to do so.

The state has about 5,000 prison employees in 22 institutions, but 'security staff numbers continue to lag behind the authorized strength,' the department's fiscal 2017 Accountability Report said, without giving numbers.

Martin said staff shortages could have been a contributing factor in the riot.

Above, a view of the prison, which houses some of the most violent offenders in the state

'When high-security inmates start engaging each other and there aren't enough staff, it's hard to stop it,' Martin said in a phone interview.

State officials identified the slain inmates as Raymond Scott, 28, who was serving a 20-year sentence for crimes including assault and battery; Michael Milledge, 44, serving 25 years for drug trafficking; Damonte Rivera, 24, serving life for murder; Eddie Gaskins, 32, serving 10 years for domestic violence; Joshua Jenkins, 33, serving 15 years for manslaughter; Corey Scott, 38, serving 22 years for kidnapping; and Cornelius McClary, 33, serving 25 years for burglary.

South Carolina Gov. Henry McMaster expressed support his state prisons chief following the riots.

His spokesman, Brian Symmes, said on Monday that the governor has 'complete confidence' in director Bryan Stirling's ability to lead the South Carolina Department of Corrections.

Stirling was appointed by then-Gov. Nikki Haley in 2013 to lead the state prison agency. When McMaster took over as governor last year, he kept Stirling, who had previously worked for him in the state Attorney General's Office.

The maximum-security facility in Bishopville, 55 miles east of Columbia, houses about 1,500 inmates, some of South Carolina's most violent and longest-serving offenders.

The prison has often been the site of violent incidents.

The riot on Sunday comes less than a month after an officer was briefly held hostage by inmates at the prison, who took control of a dorm for about 30 minutes. Another inmate was killed in February, following another inmate death last July.

Two officers were stabbed in a 2015 fight, and five were injured in a December 2007 attack by three inmates.

The State Law Enforcement Division (SLED) is assisting prison officials with the investigation.