Druze Moslem militiamen resumed their shelling of this war-battered capital today, stretching almost to the breaking point the thin hope of avoiding all-out civil war.

Lebanese Army spokesmen said five civilians were killed in the early-morning barrages of rockets and artillery that crashed into the Burj al Barajinah Palestinian refugee camp near the airport and into Christian East Beirut. Shells also exploded near the presidential palace and the residence of U.S. Ambassador Robert Dillon in the eastern suburbs.

Another in the long series of cease-fires was finally negotiated about 8 a.m., and the shelling, which had gone on for six hours, stopped. The reason for this attack from mountain positions within both Israeli-held and Syrian-held territory was unclear.

Later today, the Druze command accused the Lebanese Army of shelling Druze villages in the hills overlooking Beirut from positions around the airport. It threatened to close the airport for the third time in less than two months if the Army did not stop. The Army denied it had fired any rounds.

For many ordinary citizens here this morning's shelling raised fresh alarm that President Amin Gemayel's frail effort to effect a national reconciliation would soon fail. A money changer in the busy west Beirut commercial district spoke of the "panic buying" of dollars by persons talking about leaving. For weeks now, long lines of people wanting U.S. visas have been forming outside the U.S. Consulate two hours before it opens in the morning, and the consulate is always packed during the day.

A busboy quietly asked an American customer at a restaurant today, "How much is a ticket to the U.S., one way?"

Others are fleeing to Cyprus or Europe.

But if the ordinary citizen is despairing, sectarian leaders here give every indication of being uncompromising. During lulls when real shells are not falling, they constantly threaten and snipe at each other in newspapers and magazines.

Interviewed in the Paris-based Lebanese magazine Mostakbal, Druze leader Walid Jumblatt repeated his demand that an "amicable agreement" be made with the Druze before the Army is sent to the Chouf Mountains to replace the Israeli forces that are pulling out.

"Otherwise a terrible massacre will occur," Jumblatt warned.

During the weekend Gemayel sent three of his ministers to meet with two opposition leaders, former prime minister Rashid Karami and former president Suleiman Franjieh. Lebanese Christian leader Camille Chamoun, also a former president, attacked the ministers' mission, calling the opposition leaders "Syrian agents."

Chamoun and Gemayel's father, Pierre, the leader of the dominant Christian Phalangist Party, caused an uproar in the Moslem community here after they met with Israeli Defense Minister Moshe Arens last week.

Chamoun and the elder Gemayel appeared to find vindication in reports that Syrian Defense Minister Gen. Moustafa Tlas had visited Syrian troops in eastern Lebanon over the weekend. In long declarations quoted in the press here today, both questioned why the Moslems had not rushed to condemn Tlas' visit.

Meanwhile, state-controlled Syrian media insisted that no Lebanese reconciliation could be achieved without cancellation of the Lebanese-Israeli agreement on withdrawal of Israeli troops from Lebanon.