WASHINGTON - The United States says it is investigating the deaths of two of its citizens in South Sudan's bloodshed as it renewed calls for a ceasefire in the young nation.
Linda Thomas-Greenfield, the assistant secretary of state for African affairs, told lawmakers that the United States has evacuated 450 citizens and was urging some 200-300 Americans still in South Sudan to leave immediately.
Four US servicemen were injured in one of several evacuation flights, which have ceased.
The two dead Americans were of Sudanese descent, Thomas-Greenfield said, adding that the United States was ascertaining details about the circumstances in which they died.
Another US official, speaking on condition of anonymity, said that the slain Americans did not appear to be targeted due to their US citizenship.
The world's newest nation, which gained independence in 2011 after decades of war against Sudan's Arab and Muslim-dominated government, has been engulfed in more than a month of fighting.
Estimates put the death toll anywhere between 1,000 and 10,000 people, with hundreds of thousands displaced.
Thomas-Greenfield renewed calls for all sides to end fighting, negotiate through their differences and allow immediate humanitarian access to civilians in need.
"Neither the United States nor the international community will accept the armed overthrow of the democratically elected government of South Sudan," she said.
"I'm gravely concerned that the crisis in South Sudan has the potential to escalate even further. South Sudan's leaders on both sides are breaking their promises to their own people."
The United States has been a major benefactor of South Sudan and special envoy Donald Booth has been shuttling across Africa over the past month aiming to persuade President Salva Kiir and his rival, former vice president Riek Machar, to enter talks.
Representative Ed Royce, the chairman of the House Foreign Affairs Committee, said a failure to resolve the South Sudan crisis "will cost countless human lives and all but guarantee state failure in a strategically important region."
But the California Republican warned that "US standing in Africa is also at stake."
"If we don't leverage our considerable influence to help resolve this crisis, our ability to influence events on the continent of increasing economic, political and security importance will also surely shrink," he said.