Angry Palestinian guerrillas and Lebanese leftists poured into the streets today, firing off long bursts from automatic weapons and blocking streets with burning tires.
The Syria-dominated peacekeeping forces watched without intering.
It was the first time a resurgence of the old Wild West atmosphere has been tolerated here since Syria intervened to halt the Lebanese civil war a year ago.
Most of the shooting and explosions took place in the vicinity of the Egyptian embassy, which was hit by a rocket last night. When a column of demonstrators tried to reach the embassy again today, peacekeeping troops turned them aside.
Beirut's Christian neighborhoods presented a contrasting picture of calm, reflecting the conservative Lebanese Christian community's studied lack of concern with Arab causes.
Many Lebanese Christians residing in Moslem areas, however, have crossed into Christian or relatives as a safety precaution.
Traffic continue to pass back and forth across the dividing line today, but the level was less than normal and died away at dark.
Lebanese television carried no broadcasts of Sadat's meeting with Israeli Prime Minister Menahem Begin.
However, residents living in both Moslem and Christian neighborhoods crowded into the living rooms of friends who live in high-rise apartment buildings, to watch the historic event on Israeli television.