Prisoners at a detention centre in South Sudan's capital Juba staged a riot early on Sunday, seizing weapons from a storeroom and triggering a stand off with guards, a security source and residents in the area said.
Detainees demanded the release of political prisoners, Voice of America reported, quoting some of them. A south Sudanese government spokesman could not immediately be reached for comment.
South Sudan has been gripped by lawlessness since 2013 when a political disagreement between president Salva Kiir and his former deputy Riek Machar deteriorated into a military confrontation.
A security source said some guards at the detention centre had helped enable the riot.
"It is true, prisoners have taken over the facility from inside through the help of some officers," the national security source told Reuters, adding the detention centre, called Blue House, had been sealed off.
Voice of America said the centre housed 400 prisoners and that half of them had joined the riot.