0211 GMT May 07, 2021
Detainees said by phone that they were demanding the release of political prisoners, Reuters reported.
The rioters were caught in a standoff with guards and the center, called Blue House, had been sealed off, the security source added.
A South Sudanese government spokesman could not immediately be reached for comment.
South Sudan has been gripped by conflict since late 2013 when rivalry between President Salva Kiir and his former deputy Riek Machar deteriorated into clashes between their supporters, then civil war.
“Prisoners have taken over the facility from inside through the help of some officers,” the security source told Reuters.
The center held 400 prisoners and that half of them had joined the riot.
Last month Kiir’s government signed a peace agreement with his opponents to try and end the war which has uprooted a quarter of the country’s 12-million-strong population and devastated the economy.
On October 1 the president’s spokesman, Ateny Wek Ateny, told local broadcaster Radio Tamazuj that all political detainees had been released, under the terms of a separate agreement.