NAIROBI, Kenya — A top U.N. official in South Sudan says 3,000 foreign nationals remain in a strife-torn city from which American citizens have been successfully evacuated.

Toby Lanzer, the U.N.'s humanitarian coordinator, says Canadians, Australians, and British citizens remain in Bor alongside citizens from Uganda, Kenya, and Ethiopia.

Lanzer said Monday that there are tense, sporadic clashes and "fairly consistent gunfire and heavy machine gun fire" in the city.

Bor is where rebels fired on three U.S. military aircraft on Saturday. The United States said that it evacuated U.S. citizens from Bor on Sunday aboard U.N. and U.S. civilian helicopters.

The United States over the last week has evacuated 380 Americans and 300 others from South Sudan, which has seen vicious, ethnically targeted violence pulse through the nation.