An inmate has been stabbed to death at Coldingley prison in Woking, Surrey.
Madala Washington, 25 was pronounced dead an hour after being stabbed in the Category C jail.
An air ambulance, police and paramedics were rushed to the jail after the alarm was raised.
Police are investigating the death.
"As with all deaths in custody there will be an investigation by the independent Prisons and Probation Ombudsman," a spokesman said.
Steven Gillian, general secretary of the Prison Officers Association, told Sky News: "We do not comment on ongoing police investigation, but generally there has been an increase in violence, and indeed homicides, in our prisons.
"It is tragic that someone has lost their life."
The category C prison holds 500 inmates, who are not trusted in open conditions but are considered unlikely to make a determined escape.
