- Wounded service members in stable condition in Kenya, military official says
- Gunfire hits U.S. aircraft trying to land in South Sudan, Pentagon says
- U.S. troops were on mission to evacuate Americans from violence-hit city
- Pentagon trying to determine how to retry evacuation of more than 30 Americans
(CNN) -- Four U.S. service members who were about to help evacuate Americans from violence-hit South Sudan were injured when gunfire hit their aircraft as they prepared to land in Bor on Saturday, the Pentagon said.
The attack thwarted the evacuation attempt, and the three CV-22 Osprey were diverted to Uganda, where a different aircraft received the wounded troops for transfer to Kenya for medical treatment, a U.S. military official said on condition of anonymity.
Details about their injuries weren't immediately available; the official described their conditions as stable.
After the incident, the Pentagon was trying to determine how to retry the evacuations of roughly three dozen Americans from South Sudan, where they were working for the United Nations, a senior U.S. official said on condition of anonymity.
The evacuation attempt came after days of deadly clashes in South Sudan, including a reported coup attempt in the capital, Juba, last weekend. Bor also has been the site of heavy fighting, the U.S. official said.
The violence prompted the United States and other nations to take steps to protect their citizens. U.S. President Barack Obama had sent 45 service members to South Sudan to support U.S. personnel and the American Embassy; the government of neighboring Kenya said it would send troops to help evacuate 1,600 Kenyan citizens.
Up to 100,000 people have been displaced by the fighting so far. Many of the displaced people have crossed the Nile River, he said, adding that he feared a humanitarian disaster was unfolding.
Details of attack
The U.S. troops were getting ready to land in Bor when gunfire from the ground hit the aircraft, Pentagon spokesman Rear Adm. John Kirby said.
The Osprey that was most severely damaged was believed to have been hit in the fuel line, according to the military official who was speaking on condition of anonymity.
All three aircraft were diverted to Entebbe, Uganda, which is not where their flights originated, the official said. Another aircraft then flew the wounded to Nairobi, Kenya, where they were treated, according to the official.
Tensions rose after president sacked Cabinet in July
South Sudanese President Salva Kiir blamed soldiers loyal to his former vice president, Riek Machar, for starting this month's violence.
Tensions have been high in South Sudan -- which became the world's newest country when it split from Sudan two years ago -- since Kiir dismissed Machar and the rest of the Cabinet in July. The move inflamed deep tensions between Kiir's Dinka community and Machar's Nuer community.
Casualties are in the hundreds, including soldiers, the government said.
U.S. said Friday it was sending envoy
A day before Saturday's aborted evacuation attempt, U.S. Secretary of State John Kerry said he was sending a special envoy -- Ambassador Donald Booth -- to South Sudan.
"Now is the time for South Sudan's leaders to rein in armed groups under their control, immediately cease attacks on civilians, and end the chain of retributive violence between different ethnic and political groups," Kerry said in a statement. "The violence must stop, the dialogue must intensify."
Also on Friday, U.S. National Security Adviser Susan Rice recorded an audio message to the South Sudanese people.
"I ask each of you to make the choice for peace -- make the choice for a unified and cohesive South Sudan," she said. "Make this choice for yourselves and your children."
Indian peacekeepers, civilians killed in Thursday attack at U.N. base
Saturday's violence wasn't the first to harm foreign troops in South Sudan this week. Attackers killed two Indian army peacekeepers, wounded a third in the chest, and killed at least two refuge-seeking civilians in an assault on the United Nations' Akobo base Thursday, the U.N. said.
As many as 20 of the 30 civilians seeking refuge there might have been killed, U.N. officials estimated.
South Sudan became the world's newest country in July 2011 when it gained independence from Sudan.
The split happened after a 2005 peace agreement ended years of civil war between the largely Animist and Christian south and the Muslim-dominated north. The deal led to a January 2011 referendum in which people of the south voted to secede from Sudan.
CNN's Mading Ngor, Marie-Louise Gumuchian, Zain Verjee and Clare Hayes contributed to this report.
