About 400 Palestinian guerrillas sailed from this port today as their comrades saluted them with volleys of gunfire that echoed throughout the harbor. It was the start of a 14-day evacuation of thousands of Palestinian and Syrian fighters from this war-battered capital.

The ferry carrying the guerrillas steamed to the port of Larnaca in Cyprus, where the fighters clambered off Sunday morning waving rifles and chanting "Force Until Victory," Reuter reported.

The evacuees were scheduled to proceed in a bus convoy to the airport later in the day to take planes to their final destinations in Jordan and Iraq. The trip from Beirut took about 15 hours.

For almost two hours starting at 11:25 a.m. (5:25 a.m. EDT), a relay of military trucks brought the sometimes waving, effusive fighters identified as guerrillas of the Syrian- trained and commanded Palestine Liberation Army and of an Iraqi-backed contingent of the Palestine Liberation Organization to the loading ramps of the Cypriot ferry Sol Georgios.

Both groups, wearing green uniforms, filed on board armed with automatic rifles under the watchful eyes of French peace-keeping paratroopers, who had arrived only nine hours earlier, and soldiers of the Lebanese Army. Israeli soldiers and members of the Christian Lebanese militia watched the first stage of the exodus from rooftops and behind the closed chain-link fence outside the port's bomb-damaged docks.

Repeated volleys of automatic rifles, machine guns and antiaircraft fire sounded over the harbor during the entire evacuation. Palestinian fighters in the city fired their weapons in celebration of the departure from Beirut in what they say publicly that they consider to be a political victory. The ferry, which left about 2 p.m., rounded Beirut harbor's cement breakwater and headed into the Mediterranean Sea.

Correspondent Dash, who filed this dispatch by telephone to Jerusalem, was unable to complete his report because the phone line went dead and communications links could not be restored. The Associated Press added the following in a dispatch filed at about the same time as Dash's report:

Some of the PLO guerrillas, wearing garlands of white flowers around their necks and in their hair, settled into striped lounge chairs on the canvas-topped upper deck of the white, twin-stacked ferry. Others waved wistfully as they pulled out of the Lebanese capital, their home for 12 years.

Israeli Defense Minister Ariel Sharon, architect of the invasion that began 11 weeks ago to rout the PLO in Lebanon, watched the withdrawal at the Beirut port and said the guerrillas had suffered "a crushing defeat . . . . It is a blow from which it will be hard to recover."

"The PLO has lost its kingdom of terrorism," from which it carried out "the cruelest, most atrocious terrorist actions against Israel and throughout the world," Sharon said. He said Israeli troops encircling West Beirut would remain on maximum alert until the two-week evacuation was complete and warned that if there were any delays, Israeli forces would resume heavy shelling.

The evacuees' boat was trailed by a French gunboat for security. Another 1,000 guerrillas, bound for Tunisia, were preparing for evacuation by sea from West Beirut in the next step of the withdrawal starting Sunday.

Lebanese Prime Minister Shafiq Wazzan said the nearly 400 fighters from the Badr Brigade of the Palestine Liberation Army, originally based in Jordan, and the Iraqi-backed Arab Liberation Front departed in the first wave.

As the guerrillas arrived in the port, they flashed victory signs and brandished portraits of PLO chief Yasser Arafat on the muzzles of their guns. They waved red, white, green and black Palestinian flags and chanted "Revolution, Revolution Until Victory" and "I Love Palestine" on their two-mile truck trip from West Beirut's municipal stadium to the harbor. Many women along the route wept and waved handkerchiefs from balconies.

It was unclear whether today's exodus marked the beginning of lasting peace in war-battered Lebanon, where tens of thousands of Israeli and Syrian soldiers remain.

Sharon warned that "the Syrians have a problem. . . . Damascus, all of Damascus, is in range of our artillery," a reference to Israel's positions in eastern Lebanon's Bekaa Valley, where the Israelis battled the Syrians in the first days of the invasion and where more fighting was feared. Sharon said Israel's guns were about 15 miles southwest of the Syrian capital.

U.S. presidential envoy Philip C. Habib, who crafted the PLO evacuation agreement, is expected to begin talks soon on getting Israeli and Syrian troops out of the country. Habib was thanked by Sharon, and the U.S. envoy personally superintended the neutralization of the Beirut port to set the guerrilla exodus in motion.

U.S. officials expressed satisfaction as the first PLO units were evacuated without incident, but they cautioned that future flare-ups could occur, Washington Post staff writer Don Oberdorfer reported in Washington. They noted that the units that departed Saturday were considered among the most disciplined of the Palestinian forces.

President Reagan flashed a "thumbs-up" sign when reporters asked for his assessment of the withdrawal as he boarded Air Force One in Phoenix to fly to his California ranch. "Our reports indicate everything is going smoothly, according to plan," Larry Speakes, the deputy White House press secretary, told reporters.

Residents of Christian East Beirut crowded around radios, applauding when news bulletins gave updated reports on the guerrilla departure. "Millions of thanks to Mr. Habib. There will be peace and our city will be one once again," clothing merchant Carlos Berberian said.

Although the evacuation went smoothly, there was an initial delay in getting Lebanese troops to take over the port from the Israelis and Palestinians.

Shortly before 6 a.m., an Israeli colonel met the French ship Dives, carrying 350 paratroopers, and a surprised French colonel, who expected the Israelis to have already withdrawn from the area, asked: "What are you doing here? When are you leaving?"

"We are ready to leave when your soldiers land," the Israeli answered.

French Ambassador Paul-Marc Henry, the ranking French official at the port, said, "I'm worried because I don't see the Lebanese Army."

A Lebanese Army colonel pulled up in a car, and the French colonel began shouting at him and asking where his men were.

"They would not let us in," the Lebanese officer said. It was not clear to whom he was referring.

By noon, however, the problem was solved and Lebanese soldiers and French paratroopers took up positions.

Another potential snag arose when an Israeli driver escorting two Western journalists in West Beirut was taken prisoner by Palestinian guerrillas this morning. But Israeli Army radio reported tonight that the driver was released to American mediators after being held for several hours.

The French paratroopers who arrived today are the first contingent of a force of more than 2,000 foreign troops that is to oversee the departure of more than 7,000 PLO guerrillas, 1,500 Syrian soldiers, and 2,500-3,000 Syrian-commanded Palestinians during a 14-day period.

The United States is contributing 800 Marines to the peace-keeping force. They are to arrive on about Thursday, and Reagan has said they will play a "carefully limited, non-combatant role" of no more than 30 days' duration and will be withdrawn if fired upon. An additional 450 French soldiers and 530 Italian troops will round out the peace-keeping force.

By Wednesday about 3,000 guerrillas are supposed to have left Beirut by sea, using Cyprus as a staging point before dispersing to Jordan, Iraq, South Yemen, North Yemen, Sudan, Algeria and Tunisia. Egypt has said it will take severely wounded guerrillas.

The bulk of the Palestinian forces will depart by bus to Syria, beginning Wednesday. Syrian sources say scattered camps are being readied to house 8,000 Palestinian fighters temporarily.

The Syrian sources said Syria has agreed to keep 5,000 indefinitely. The rest will be dispersed. Arafat is expected to set up a headquarters in Tunisia.

The withdrawal is scheduled for completion by Sept. 4, and all members of the multinational force are due to leave the country by Sept. 26.

Some of the Palestinians and Syrians in Beirut may not leave Lebanon, however, and some are expected to return shortly to join the Syrian soldiers in the Bekaa Valley.