A chartered DC10 carrying U.S. Embassy employes and their families left here this morning for Nairobi, Kenya, as part of an evacuation ordered as a precaution against terrorist attacks.

The plane lifted off Khartoum International Airport shortly after dawn. The take-off followed a long night here for Americans and their families, who traveled around the city with their luggage to secret gathering points.

Traveling in unmarked embassy vans and four-wheel-drive vehicles, between 200 and 300 Americans began assembling at a number of locations in Khartoum around midnight. At 3:39 a.m. local time (8:39 p.m. Thursday EST) 37 vehicles converged on the airport from the north and south of the city.

The United Nations also planned to evacuate its American employes here and the U.S. Embassy urged private American relief agencies to do the same. Officials of the relief agencies expressed reluctance to disrupt their work in southern and western Sudan.

The U.S. Embassy ordered its "nonessential" personnel and all dependents to pack their bags and prepare to be evacuated following the shooting Tuesday night of embassy employe, William J. Calkins, in what U.S. officials here believe was a reprisal for the U.S. bombing of Libya Tuesday.

U.S. officials here said Calkins, an embassy communications specialist, has suffered a serious brain injury and is partially paralyzed from the bullet wound. He was flown Wednesday to a hospital in Saudi Arabia where he was reported in stable condition after surgery.

The official Suna news agency reported that Sudan had recalled its ambassador in Washington, Salah Ahmed, to protest the U.S. attack on Libya.

An embassy spokesman said the evacuation was ordered "because of the deteriorating security situation in Khartoum, the shooting of the American and the calls for anti-American attacks by the Libyan government."

In the past month, the Sudanese government has dramatically improved its relations with Libya, while relations with the United States have become strained. Recent Libyan military aid for Sudan's war against southern rebels partly accounts for the realignment. There is also widespread outrage in Khartoum over the U.S. bombing of an Arab ally.

U.S. Embassy officials met yesterday with leaders of American relief agencies in charge of the famine relief program in Sudan. They were advised to send all nonessential staff and their dependents out of the country as quickly as possible.

Several relief agency directors said after the meeting that they did not believe there was a significant threat to Americans working outside Khartoum the capital and largest city in a vast and sparsely populated a relatively empty nation. They added that most of their American employes would not leave at this time. The Americans flown out this morning included a number of relief workers from private agencies and U.N. staff.

"Right now, it is business as usual," said Andrew Pugh, an administrator for CARE, which has 15 Americans working in Sudan. "A lot of our people are out in remote villages and the people there probably haven't even heard about all this."

Among the Americans evacuated were H.D. Swartzendruber and his wife, Frances, who live in Reston and who came to Khartoum six weeks ago. They both worked here as consultants to World Vision, helping to organize distribution of U.S. AID food.

"We have traveled a lot in our work, and we have been caught up in three coups . . . . we were never targeted as Americans," Swartzendruber said. "But in this case, it didn't seem sensible to make the U.S. Embassy have to worry about a couple more Americans than they have to."

Samir Basta, director here for UNICEF, said U.S. concern about possible Libyan attacks against Americans had caused U.N. officials to order most American U.N. employes out of Sudan.

Western intelligence officials here said there are about 200 Libyan government employes in Khartoum and several of them are believed to be trained and experienced in terrorist attacks.