Updated

The Latest on four inmates authorities said were killed by two other prisoners in South Carolina (all times local):

2 p.m.

Autopsies on four inmates found dead inside a cell in a South Carolina prison say they were all strangled and were killed within 30 minutes of each other.

Richland County Coroner Gary Watts said in a statement that 52-year-old John King was choked with an electrical cord on Friday morning at Kirkland Correction Intuition in Columbia.

Watts says the killers of 44-year-old William Scruggs strangled him while pressing on his chest, while 35-year-old Jason Kelley and 56-year-old Jimmy Hamm were also strangled.

The coroner says all four inmates died between 10 a.m. and 10:30 a.m. on Friday.

Two inmates serving life sentences — each for killing a mother and her child — have been charged with four counts of murder in the killings. Prison officials say they are being held in the system's highest security area.

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9:50 a.m.

Two convicts each serving a life sentence for killing a mother and her child have been charged with murder in the strangulation deaths of four inmates inside a South Carolina prison.

Arrest warrants released early Saturday say 35-year-old Denver Simmons and 25-year-old Jacob Philip lured each inmate into a cell at Kirkland Correctional Institution in Columbia on Friday morning.

The warrants say the men worked together to choke all four inmates. Two of the victims were also beaten and stabbed with a broken broomstick.

The warrants gave no reason for the attack or how long the killings took. Prison officials are investigating the attack and have not commented. The warrants say there is video.

It wasn't known if the inmates had lawyers.