In a scene that captured both the chaos and pathos of this divided city, 10 tearful Americans were evacuated from Moslem west Beirut today to the relative safety of the city's Christian sector. They left amid a frantic rush of screeching tires and speeding jeeps, crammed with nervous Druze militiamen holding up pistols and machine guns as they escorted the Americans to east Beirut.

Militiamen guarding the blocked-off and deserted U.S. Consulate, where the evacuees gathered early this morning, could not conceal their astonishment at the sorrow of the departing Americans.

"They are all crying. It's incredible. We're trying to leave Lebanon and they want to stay," said one grinning militiamen barring reporters from the compound.

Riding in a gray bus with a security guard standing in the door, his gun pointing skyward, and flanked by Lebanese police vans and carloads of Druze fighters, five men and five women left behind careers and friends.

Their stubborn attachment to survival in Beirut was finally loosened by the murder of colleagues and friends in retaliation for a British-backed American air strike against Libya last week.

Martha Shaffner was shattered by the thought of leaving her Lebanese boyfriend and having to start over again. The warm climate, "wonderful friends" and her companion, known in the foreign community here as "Mike the Barber" for his ability to clip crew cuts, had attracted Shaffner, of Troy, Ohio, to settle here years ago.

"I like it here, I have no future elsewhere, I have made this my home," she said, sobbing. "But when I can't walk on the streets anymore, then it's time to leave. I have been sitting at home, being afraid. I am no longer free."

One of the saddest evacuees was Thomas Weaver, who came here in 1947 to teach at a Lebanese high school called the International College. Weaver said he hoped to come back. Something of an institution in the cultural life of west Beirut, Weaver, a tall bachelor with silver gray hair, has devoted his life to music and drama clubs he founded here.

"What are we going to do back there in the United States ? We have nothing," said Tabitha Petran, a writer from New York City and a west Beirut resident for the last 15 years.

Although U.S. Embassy officials refused to disclose details of the travel plans or whereabouts of the 10 Americans, some of them were put up at the homes of Americans residing in the Christian-controlled area until they could arrange trips to Cyprus and elsewhere.

About 20 Americans remain in west Beirut. Some are professors wishing to complete the term at the American University of Beirut.

"I am coordinating a program with 1,270 students. I now have nine out of 25 full-time teachers. The responsibilities are enormous. I will not set foot outside the campus for the next two months, but I just cannot leave right now," said an American who stayed behind.

Phil Grant, a political science professor from Santa Barbara, Calif., expressed disappointment at not being able to complete the semester but noted that he could no longer invent rationales for staying after the assassination of his colleague, Leigh Douglas, one of the Britons slain last Thursday.

Grant said the two years he spent here allowed him to learn more about the United States and himself than he would have at home.

"What I enjoyed the most was seeing the U.S. and my background from another center of gravity," he commented while packing his books in cardboard boxes yesterday. "The U.S. has a unique place in the world. It is a sort of sun that casts a very, very dark shadow. Everyone looks to the United States as a place to escape to and where dreams can be pursued, but the defects of the U.S. are seen in a very severe light. That's the thing President Reagan cannot understand, the shadow."

"The use of force against Libya, for example, is based on a misunderstanding of the history of the Arab world, the ideals of Libyan leader Muammar Qaddafi and the tactics and strategy that revolutionaries pursue," Grant commented.

Shaffner, though upset at having to leave Lebanon for reasons beyond her control, said she supported Reagan, "Yes, something has to be done with this man in Libya," she said.

The dwindling number of Americans and Britons on the faculty of the university is seen as a setback to its 11-year struggle to remain above the strife here. A university spokesman said English and American professors would be replaced by Lebanese, but that accreditation and standards were likely to suffer. Last Sunday, 32 Britons, a New Zealander, an Irishman and an American were evacuated to east Beirut by the British Embassy.

Western diplomats and relief agency sources said the International Committee of the Red Cross has withdrawn all foreign staff members who are not Swiss. The U.N. Relief and Works Agency, which administers relief and education for Palestinian refugees in Lebanon, has also pulled out Irish and Austrian administrators.

The American University Hospital shut the doors of its emergency room today, until further notice, to protest attacks against its doctors and nurses yesterday by local militiamen. The last foreign doctor on the university staff, a Briton, left west Beirut Sunday.

Many Moslem leaders have criticized the latest rash of kidnapings and killings targeting westerners and have sounded the alarm over the future of schools and universities.

Druze leader Walid Jumblatt criticized Arab governments for ensuring the safety of westerners in their own countries while urging activists to attack them in Lebanon.

Once the meeting place of exiled intellectuals from all over the Middle East because of its tolerance of diversity and its variety of hotels, boutiques and cafes, west Beirut now offers only a life under siege.

Grant, not previously an expert on the Middle East, said he would like to study the Arab world somewhere else.

"Here all your energies go into living, as opposed to thinking," he said.