U.S. military planes have evacuated Americans from South Sudan amid continued political violence there, the State Department announced today.

"This morning we safely and successfully evacuated three groups of U.S. citizens from South Sudan," department spokeswoman Marie Harf said in a written statement. "Two Department of Defense C-130 aircraft and a private charter flight departed Juba at 0530, 0535, and 0940 EST, respectively, carrying non-emergency Chief of Mission personnel, private U.S. citizens, and third country nationals."

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South Sudan President Salva Kiir said Monday that his army had quelled a coup attempt by soldiers loyal to a rival, and the government announced that 500 people have been killed in South Sudan since Sunday, The Associated Press reported.

The United States Tuesday ordered non-emergency personnel out of the country and advised all Americans to leave, but the embassy remains open for Americans who need help getting out of South Sudan, and key diplomatic personnel remain in place. The U.S. ambassador to South Sudan, Susan Page, spoke Tuesday with Kiir, the State Department said.

Meanwhile, 13,000 people have taken shelter in a U.N. compound on the outskirts of Juba, the U.N. has said.

The Pentagon has also announced its role in the evacuation from Juba and leaving behind a military team at the embassy.

Pentagon spokesman Col. Steve Warren told reporters that the C-130s had come from the U.S. military base at Djibouti.

The planes also carried in members of the U.S. military's East Africa Response Force (EARF) who have remained behind in Juba to protect the U.S. embassy. The EARF is one of the two U.S. military quick-response forces for Africa established after the Benghazi consulate attack. The 500-Marine force based in Spain is responsible for North and West Africa, while the smaller 100-man (mostly Army) EARF is based in Djibouti and can respond to emergency situations in eastern Africa, as happened today.

Diplomats from other countries were also flown out aboard the U.S. military aircraft, Warren said.

He would not disclose the size of the EARF force left behind in Juba but said that "we believe it's a force sufficient in size based on the situation."