Soldiers have been deployed along the Juba-Nimule road to maintain security, SPLA spokesperson has said.
This follows an attack on a passenger bus along at Ame junction on Thursday.
Four dead bodies were brought to the Juba teaching hospital, but other security officials said at least five people were killed.
Col Philip Aguer confirmed that four were killed, and 17 others wounded in the incident.
He told Eye Radio that soldiers were still pursuing the attackers.
“This is an act of terrorism and these people have been committing crimes against innocent civilians on the road,” Col Aguer stated.
He did not specify how many soldiers have been deployed on the road.
Last week, police and security forces seized guns during a patrol along the Juba-Nimule road. Some suspected criminals were arrested during the patrol.