Seven inmates died in clashes on Sunday night in a US prison, violence among the worst of recent decades in a country with highly criticized prison policy.

The riot was opposed by rival groups of prisoners at Bishopville Penitentiary Lee, a facility frequently shaken by unrest in the state of South Carolina.

The situation became out of control at 19:15 (23:15 GMT) with “many fights in three residential buildings,” said the prison administration of that state in the south-east of the country.

There were no guards or policemen wounded in the violence, but “17 detainees required medical treatment outside the facility, and seven detainees were killed,” the authorities said.

Calm was restored at 2.55 am on Monday morning, according to the prison services, which did not provide details on the violence, but thanked the police and emergency services mobilized.

The heavy toll, succinctly announced Monday on Twitter, illustrates the harshness of the American prison world that is often criticized for its lack of humanity, pushing many prisoners to despair.

The US prison population is at an all time high, with approximately 2.2 million people behind bars, including legions of mentally ill and delinquent offenders.

Violent prison world

Bishopville’s high security prison in Bishopville hosts some of the most dangerous male convicts in South Carolina.

It was built in 1993 with a capacity of nearly 1800 places, for convicts serving sentences often long.

Violence and mutinies are relatively frequent.

Inmates had neutralized a guard in March and took control of part of a dorm, local channel WACH Fox reported.

One inmate lost his life in a fight in February, another was fatally wounded in November, and a third was killed in July 2017 in an altercation.

The Democratic Minority Leader of the South Carolina Parliament Todd Rutherford said it was “unacceptable” that such an event, with many victims, could happen inside a penitentiary.

“It’s a symptom of a broken judicial and criminal justice system that needs to be reformed,” he tweeted.

An investigation has been opened into the facts that have plunged Lee prison, the balance sheet being among the heaviest in a quarter of a century.

South Carolina Republican Governor Henry McMaster was due to speak in the afternoon.

In 1993, nine inmates and one prison officer were killed in a very high-security prison in Lucasville, Ohio, in the north.

A mutiny in a state prison in New Mexico (south-west) resulted in the death of 33 detainees in 1980, with some 200 wounded.

The trauma of Attica

But the uprising that has most marked American history remains the mutiny Attica, a penitentiary in the northeastern United States that had a majority of black and Puerto Rican prisoners.

This rebellion broke out on September 9, 1971, before being quelled four days later in a bloody repression.

Some 1,300 detainees had taken control of Attica’s buildings, keeping custodians and prison staff hostage.

New York Governor Nelson Rockefeller decided to send the troop: hundreds of police and national guards opened fire on the unarmed mutineer rifle.

Twenty-nine prisoners and ten hostages had been killed, and a hundred men seriously injured.