JERUSALEM -- The mass demonstrations of the Palestinian uprising have given way to clandestine squads of armed men operating in the shadows of violence and fear.

No longer do crowds of men, women and children daily confront Israeli troops; the struggle for the occupied territories of Palestine is now one of midnight murders and sudden gunfights.

Guns have replaced rocks as the weapon of the "intifada" uprising. Incidents of shootings by Palestinians have soared to all-time highs this year, and secretive Israeli squads are accused of executing suspects.

The who and why of the killings is not always clear, but far more Palestinians are being killed by other Palestinians than by Israelis. Brutal groups with names like Black Panthers have killed 71 Palestinian suspected "collaborators" so far this year.

At the same time, Israeli special units disguised as Arabs are increasingly involved in controversial shootings. Human rights groups allege that the units have secret orders to shoot to kill and that they have slain unarmed, innocent, or unresisting Palestinians.

"What we see today is armed struggle," said Yazhar B'eer, head of an Israeli human rights organization, B'tselem.

"You can't see the big demonstrations any more, the big masses coming out against the army," he said.

"It has quieted down," agreed Yasser, a 20-year-old Palestinian with pale brown eyes sitting in the Jabaliya Refugee Camp in the Gaza Strip. In this desperate place of tin shacks, dirt streets and open rivulets of sewage, the intifada began and blossomed. Now, says Yasser, a veteran of hundreds of demonstrations, "the people are in a waiting phase."

Most are weary of the confrontations, the thousands of arrests, the tear gas and shootings, the curfews and strikes that have impoverished the territories. They want to give U.S.-sponsored peace talks a chance.

But others have dropped the stones that are a symbol of the Palestinians' underdog struggle and have taken up arms in the occupied territories where, not so long ago, it was unthinkable for a Palestinian to be carrying a gun.

"It is a very dangerous game," said Hanan Ashrawi, a Palestinian delegate to the U.S.-sponsored peace talks. "You corner people. You put them in this pressure cooker. People will conduct desperate acts."

Twenty Israeli civilians and 12 soldiers have been killed in the 4 1/2 years of the Palestinian uprising. But overwhelmingly the casualties have been and remain Palestinians -- more than 1,400 killed since the intifada began in late 1987.

In the spasms of violence at the beginning of the intifada, Israeli soldiers killed dozens in chaotic skirmishes with large crowds. Now, Palestinian groups such as the Black Panthers are killing more Arabs than the Israelis, often hacking and butchering their victims to show what happens to collaborators.

"In their own way, they are what the intifada is today: small terrorist groups killing more Palestinians than the Israelis, becoming increas ingly alienated from the population," says Lt. Col. Moshe Fogel, an Israeli Army spokesman.

Yasser Abu Ali is a soldier in this war. He is 21. He wears high-top sneakers with bright red shoelaces and fashionable jeans bound tightly at the ankles "to run better."

He also wears a 14mm revolver. That is enough to make him likely to be shot if he is spotted by an Israeli patrol. He is a member of the Black Panthers, with a membership card with a serial number and the slogan, "Revolution until Victory."

To meet him and two other Black Panthers required a circuitous, 11-hour journey, passage from one contact to another, a secretive change of cars, and finally a two-hour wait in an olive grove. The interview took place surrounded by lookouts, at a village close to Jenin, a town that is a stronghold of the Panthers.

Yasser Abu Ali says he joined the Black Panthers because six of his friends were killed, and "this is my revenge." He has not slept at his home for 18 months because the Israeli army and their informants watch for him there.

He has not killed, he said. One companion, Jelal Ibrahim-sheik, said he shot a collaborator in the kneecap. A third Panther, Iyad Abu

Ashka, has three nasty bullet scars in his back from a recent escape from soldiers.

Within days of the interview, Black Panthers in the same area claimed responsibility for killing a mother of seven and an Arab doctor with links to the Israeli government.

"Those are the ones who are doing the damage to our people the most," Yasser Abu Ali had said of collaborators. But the group's targets include "loose" women, rivals, drug users, sometimes innocent people.

In a village nearby, Subhia Jamil Muhar, 45, wondered how to feed her six children after the death of her husband, Jamil. He was severely beaten, apparently in an interrogation by the Red Eagles, a group like the Panthers.

ZTC The next day the Red Eagles announced he was innocent. It was too late: Mr. Muhar died at his home a few hours after the beating.

"I don't know why he died," said his wife, clearly frightened. "He didn't socialize much."

Despite their internecine bloodletting, these groups enjoy a measure of popular support. Lacking their own police, laws, or courts, the Palestinians see Black Panthers as attempting to exact some rough justice.

"When they march with their guns, children gather around them," said a resident of Jenin.

Palestinian leaders have occasionally tried to curb the violence of the groups' members, estimated at fewer than 200. But critics cannot be too vocal: Some have been threatened and beaten.

Panther Jelal Ibrahim-sheik, who is 18, predicts his activities will end in death: "I will become a martyr for the sake of the homeland."

Israeli undercover squads are trying to assist in that, some allege. These special agents speak fluent Arabic, drive cars with local license plates, and often emerge from the disguise of an Arab woman's dress when they spot a wanted person.

They sometimes emerge shooting, contends Faisal al-Husseini, a Palestinian political leader. He recently charged that Israeli squads have killed 18 young men this year who were unarmed or did not resist.

Military authorities deny the charge. The Israeli press carries almost daily accounts of Palestinians wounded or killed during an arrest. Palestinians are convinced the mission of the squads is execution.

In a poor home on a high ridge in Jenin, Fatma Ismael Fahmawi said that that is what happened to her son, Khalid, 19.

He was a wanted man. "To the Israelis they are bad, but every honest Palestinian thinks the Black Panthers are something to be proud of," said the mother. On the gray cement wall above her hung a picture of Khalid, resting an automatic rifle on his shoulder.

She insists Khalid was unarmed when he was arrested March 12 at the home of a relative, where he went to spend a night with his bride, 15-year-old Salma. The army said he pointed a gun at the soldiers.

B'tselem estimates 70 Palestinians have been killed by undercover units since the beginning of the intifada. The human rights group contends that "there is a policy, and clear orders exist, to 'wipe out' " the most wanted of the Black Panthers.

It has compiled a list of what it calls questionable killings, including:

* A 23-year-old wanted man killed March 22 as he played a soccer game in a stadium. B'tselem said there was no escape; the unarmed man tried to hide behind a referee but was shot. An army spokesman said the shots were intended to wound the man only enough to prevent his escape.

* A 19-year-old killed at night March 18 walking home after delivering a cow to a nearby village. A companion said they accidentally walked into an Israeli stakeout. The Army claimed he was armed with a knife and iron bar.

"More and more Palestinians are being killed by these units," said Mr. B'eer, head of B'tselem. "We have evidence that in some cases, they killed people they could have caught."

A spokesman for the Israeli defense forces said some cases are under investigation, but that most undercover units act properly.

"No one can argue with the fact there is more use of firearms by the Palestinians," the spokesman said. "To expect them to use more weapons and not have more casualties is not logical."

Israeli denials of wrongdoing were strained last week by an unusual eyewitness account offered publicly by two Israeli civilians. The Israeli couple was visiting a Palestinian friend in a village near Hebron and saw an undercover unit shoot two unarmed Palestinians spray-painting political slogans on a wall.

"The soldiers shot at the masked men in cold blood from a distance of a few meters without giving any warning," David Elimelech told Israeli newspapers.

The case seemed to give credence to earlier, unrelated remarks by Anon Shahak, the Israeli deputy chief of staff, in an interview with the newspaper Ma'ariv.

"This is a war against murderers," he said. "We don't hold discussions with armed, wanted persons."

Inside a tiny grocery at the end of a dusty road at the edge of Jenin, Ibrahim Khalil Turqman pondered that philosophy. It may have killed his cousin.

Muhammad Turqman, 29, was killed Dec. 10 when agents of Shin Bet, the Israeli intelligence service, stopped the taxi he was in, reached into an open window and fired three shots into Mr. Turqman, according to B'tselem and the family.

The agents apparently thought he was another man with a similar name whom they wanted.

The man they killed was a Bedouin, a shepherd, uninterested in anything but his flock and his four young children, said his cousin.

Said Mr. Turqman, "He was just an ordinary man. They didn't even ask for his identity card."

KILLINGS OF PALESTINIANS IN THE OCCUPIED TERRITORIES

.. .. .. Palestinians killed by.. ..Palestinians killed by

Year.. ..Israeli security forces.. .Palestinians.. .. .. .

.. .. .. .. .. .. .. 300.. .. .. .. .. .. .. .. 18

1989.. .. .. .. .. .. .. .. .286.. .. .. .. .. .. .. ..133

1990.. .. .. .. .. .. .. .. .125.. .. .. .. .. .. .. ..184

1991.. .. .. .. .. .. .. .. . 89.. .. .. .. .. .. .. ..184

1992**.. .. .. .. .. .. .. .. 30.. .. .. .. .. .. .. .. 71

*1988 Figure includes Dec. 1987

**1992 Figure covers January through March