A group of humanitarian organizations monitoring civilian casualties in South Sudan says 80 civilians, including 57 children, were killed in just one county in war-torn Unity state between October 4 and 22.

The Protection Cluster, representing 60 local and international organizations, said 29 of the children drowned after running into swamps to hide from attacks in Leer County. The group said there were reports of widespread use of sexual violence, including more than 50 rape cases.

South Sudan army spokesman Philip Aguer said Saturday that he had no reports of fighting in Leer County.

The U.N. and human rights groups have documented widespread abuses against civilians including rapes and killings by government soldiers and their militia, in Unity state this year. Fighting persists despite a peace deal signed in August.