A 42-year-old inmate died early Saturday morning prompting all visitations this weekend at the McPherson women's prison in Newport to be canceled.
Additional doctors and nurses have been called in to treat others with symptoms and to screen the nearly 900 inmates at the facility.
Corrections officials said the illnesses are happening in housing area three.
We're told 240 inmates living there are under quarantine and are being kept away from the general population.
Corrections officials said they don't know what killed the 42-year-old woman. They say she had flu-like symptoms, but test showed she didn't actually have the flu.
At least three other inmates with similar symptoms are being treated and monitored closely.
Family members we spoke with Sunday were worried about their relatives.
"I understand they're in prison and they're state property, but they deserve care just like the rest of us do," said Ashley Whitacre whose sister is an inmate at McPherson.
Corrections officials said extra doctors and nurses were brought to treat inmates and scan all of the nearly 900 prisoners.
Correction officials said they had to go through the process of scanning the inmates.
As of Sunday, no decisions had been made as to when the quarantine will end or when visitations can resume.