High-ranking leaders of the Patriotic Front guerrilla army returned from exile today to a heroes' welcome from 15,000 supporters.

"We've been fighting to come home, and now we are free," said deputy commander Rex Nhongo of the Zimbabwe African National Liberation Army as he and 41 comrades from camps in Mozambique stepped off a British-chartered airliner.

While Patriotic Front leaders Robert Mugabe and Joshua Nkomo have yet to return under the cease-fire reached in London earlier this month, their chief lieutenants were brought in today to help carry out the terms of the truce.

The guerrilla leaders are to summon their men who have fought the Salisbury government from the bush and assemble them at control points while elections are held to lead the British colony to independence.

[In Maputo, Mozambican President Samora Machel said that "more than 350 Mozambican soldiers are today in Zimbabwe," the future name of Rhodesia. 3He said 500 of his countrymen had fought there on the guerrillas' side and 24 were killed.]

The airport crowd included followers of both Mugabe and Nkomo -- who, though partners in the civil war, are widely expected to compete in the electoral contest. There were no clashes today between the two factions.

The first to arrive was a husky soldier in a camouflage jacket and brimmed hat with a red band indicating the rank of brigadier. He was Lookout Masuku, leader of the Zimbabwe People's Revolutionary Army loyal to Nkomo.

"I am very happy to be back," Masuku said. Asked when he was last here, the guerrilla said, "A year ago, in the bush, fighting for our cause." His faction fought against the Rhodesian government from bases in neighboring Zambia.

The same plane later flew in Nhongo and the 41 officers loyal to Mugabe.

Buses took the guerrilla contingents to their asigned quarters in Salisbury, escorted by well-armed Rhodesian soldiers. A Commonwealth peace-keeping force is so small that it must leave to the Rhodesian troops such duties as guarding their erst-while guerrilla enemies.

The concern about the safety of such guerrilla leaders as Nhongo and Masuku is based on a double threat. There is rivalry among the black factions, and there is also intense hatred of the guerrillas by members of the white minority -- the former rulers -- who have lost family members in the civil war.

Rhodesian government police prevented the supporters of the guerrillas from reaching the front of the airport terminal, using leashed dogs to turn back the surges of the crowd. Although many police acted with restraint, several demonstrators and one correspondent were bitten by the dogs.

Neutral observers put the number of guerrilla supporters at 15,000 to 20,000, about the same turnout as welcomed Bishop Abel Muzorewa when he returned from the London negotiations. Muzorewa was the prime minister for six months in a government that, although dominated by blacks still left the white minority with substantial political power. This made Muzorewa, as well as many whites, the enemy of the guerrillas.

Signs in today's crowd denounced the bishop as "selling out our blood brothers."

When the Rhodesian Army tried to put two armored cars in a position to dominate the aircraft bearing the guerrilla representatives, British officials warned the cars' commanders "to get the hell out of there," and they did.

One of the armored cars had an improvised white cross on its side indicating it was a part of the British monitoring force. British officials said it was a violation of the cease-fire agreement and a protest would be made.

The chief of the British cease-fire force Gen. John Ackland, told reporters of indications that Nkomo's guerrillas were ready to "cooperate" with the implementation of the cease-fire, which reaches a critical stage on Saturday -- the first day that guerrillas are to come into 22 rendezvous points before moving into 16 assembly areas.

Rhodesian government troops are to withdraw to their garrisons to complete the separation of the foes.

"The Patriotic Front will be abandoning a way of life, moving from the clandestine into the open. The PF will be nervous, distrustful," Ackland said.

He warned that while the Rhodesian Army was clearing roads of guerrilla mines as rapidly as possible, he feared that die-hard guerrillas would reseed the dirt roads in the assembly points.