Vehicle travelers on Kajo-Keji-Juba road on Monday came under attack.
The incident happened a few kilometres away from the city leaving at least five people dead.
Anonymous survivors and transport company officials confirmed the dead include three young men and two ladies.
A Comboni Mission-Lomin staff identified as Wadok Julius was among the deceased.
The four others include Emmanuel Kanyarsuk, Nyara Charles, Juan Jane and Rose Guo.
The deceased were brought to Juba Teaching Hospital mortuary on Monday evening.
The incident is the second this week.
On Sunday, a humanitarian organization ACROSS vehicle was attacked and the passengers were reportedly stripped and later freed.