Armed rebels opened fire on a UN convoy in South Sudan’s troubled state of Jonglei, killing five Indian peacekeepers and at least seven civilian workers.

The UN convoy, with just over 30 UN soldiers, was then traveling between the South Sudanese towns of Pibor and Bor when gunmen, numbering in hundreds, opened fire on the peacekeepers and civilians, reports The Associated Press.

Five Indian troops and seven civilians, including two workers for the UN mission in South Sudan and five civilian contractors, were killed in the ambush in Gumuruk. At least nine additional peacekeepers and civilians were injured while some remain unaccounted for.

“The peacekeepers were vastly outnumbered. It was a deliberate and targeted attack,” UN peacekeeping spokeswoman Josephine Guerrero told AFP.

Col. Philip Aguer, South Sudan’s military spokesman, blamed the attack on insurgents led by rebel leader David Yau Yau.

UN Secretary General Ban Ki-moon and the UN Security Council condemned the attack in separate statements and called on South Sudan’s government to “swiftly” bring the perpetrators to justice, reports AFP.

Ban is “appalled” by the attack on peacekeepers, which he describes as a “war crime that falls under the jurisdiction of the International Criminal Court,” said his spokesman Martin Nesirky.

Internal violence has rocked South Sudan even after decades of civil war with Sudan ended in 2005. UN troops have recently stepped up their patrols to deter violence and fulfill their mission of protecting civilians.