The aid group Doctors Without Borders said a munitions explosion killed seven people and injured a child on Thursday in the South Sudanese state of Unity.
The stockpile of unexploded ordnance was stored in a container in opposition-held Thar Jath and was leftover from clashes between government forces and rebels last year.
Doctors Without Borders said in a statement on Tuesday that the container likely blew up after local residents set fire to the grass nearby to clear land for farming.