The convoy with eight staff members was attacked Thursday some 25 miles south of Nyala, the capital of South Darfur state, the United Nations reported according to The Associated Press.
Among the three wounded aid workers - all of whom were Sudanese - two were shot in the head and one in the arm. World Vision informed AP that two were in stable condition, while one was in serious condition.
"This is a horrifying and brutal attack on aid staff who are working to save the lives of Sudanese people," UN humanitarian chief John Holmes said.
The attackers have not been identified but the United Nations did note that Arab tribes have had frequent clashes in the area.
In August, World Vision announced it was expanding its operation in Darfur to meet growing number of people in need. It has already expanded from 22 food distribution sites to 38. The aid group also said it had no intention of leaving the war-ravaged region.
"We ourselves are the hands and feet of Jesus. We really urge the listeners to pray for us and to pray for our staff that God would protect them, that God will enable them to show the love of Jesus through what they do," said World Vision spokeswoman Rose Kimeu in August.
Attacks against humanitarian workers have increased by 150 per cent from June 2006 to June 2007, according to the United Nations.
"We are grateful that God has given us the opportunity to be able to show the people of Darfur the love of Christ," Kimeu said. "Every day our staff risks their lives as they go out to the community. We've had many attacks on our cars and on our staff."
Since the beginning of the year, 105 humanitarian workers were temporarily taken hostage and 66 were physically or sexually assaulted in Darfur. Moreover, 61 convoys were ambushed or looted, and 98 vehicles hijacked.
Darfur is recipient of the world's largest ongoing humanitarian effort with some 14,000 aid workers including 1,000 internationally deployed.
More than 2.5 million people have been displaced and some 200,000 people killed due to violence instigated by Arab militias known as janjaweed since 2003. Khartoum is widely accused by both Darfurians and the international community of unleashing the pro-government janjaweed on Darfurians after rebels from ethnic African tribes in the region rose up against the central government.
A hybrid force of 26,000 UN-African Union peacekeepers is due in Darfur by December 31 in a global effort to stop the violence in the region.