BEIT UMMAR, FEB. 7 -- The southern half of the Israeli-occupied West Bank exploded in violence today that left at least three persons dead and more than a dozen injured in clashes with Israeli troops.

The region had been relatively quiet during the two-month-long wave of Palestinian disturbances, but today it became the scene of one of the worst days of rioting since the protests began.

Two other Palestinians injured last week died of their wounds today, bringing the Arab death toll to at least 49 during the past two months. No Israelis have been killed in the disturbances.

One of today's dead, a 15-year-old resident of a Gaza Strip refugee camp, who died after receiving a blow to the head, may be the first fatality from the Israeli Army's policy of beating alleged rioters.

At least four neighborhoods in predominantly Arab East Jerusalem also were hit by renewed violence. The Army, invoking seldom-used emergency powers for the second time in 16 days, imposed a curfew on a refugee camp inside the city limits.

Tensions have been building in the south since the middle of last week, when some of the Jewish settlers who live in the area began organized retaliation against stone throwers in villages along the main highway. Settler vigilantes have invaded some Arab villages, smashing car windows and hauling off suspected assailants.

Then on Friday, the National Committee for the Uprising in the Territories, a clandestine steering group led by the Palestine Liberation Organization, which is outlawed by Israel, and various nationalist factions, issued its sixth leaflet calling for increased rioting and for demonstrations today. A radio station apparently broadcasting from Damascus chided Arabs in the southern city of Hebron and surrounding villages for failing to participate in the uprising of recent weeks.

The combination of the two volatile elements -- the call for protests and the panic touched off in many villages by rumors of settler incursions -- sparked the new round of violence that began last night, according to Army officers and some residents.

The worst incident was here in Beit Ummar, a small village north of Hebron, where three residents were shot dead by soldiers in a clash this morning. Witnesses said the trouble began when residents heard rumors that settlers had fired shots into the neighboring village of Arrub and were heading toward Beit Ummar, 12 miles south of Jerusalem.

Dozens of residents, urged on by cries of "the Jews are attacking" broadcast over a loudspeaker at the local mosque, blocked the road into town and threw rocks and bottles at soldiers there, the Army said. Reinforcements arrived and tried to push the mob back with tear gas and rubber bullets. When the crowd surged again toward the main Jerusalem-Hebron highway, the troops opened fire.

The Army put the total wounded at six from all incidents today, but doctors at Makassed Hospital in East Jerusalem said they alone had received 12 gunshot wound victims today, seven of them from Beit Ummar, and 11 people with injuries from severe beatings.

Rami Akluq, 15, died in Gaza shortly after he arrived at the hospital this afternoon with head wounds he suffered yesterday at the Deir Balah refugee camp in Gaza. The boy's father told doctors his son had been struck by soldiers after he tried to flee from a group of them in panic.

An Army spokesman attributed the death to "totally medical causes." He noted that the body had no other signs of injuries and denied the boy had been beaten. But Drs. Rustam Nammari and Hani Abdeen, speaking to reporters, said the boy's injuries were consistent with being clubbed on the head.

The Army also reported that a 10-year-old boy died of wounds he sustained five days ago in the village of Burqa when he was struck in the head by a ricocheting bullet.

The scene at Makassed Hospital this afternoon was one of chaos as ambulances and private vehicles poured in with victims from remote villages around the West Bank and relatives filled the hallways.

Atlia Hassanat, 19, from the Dehaishe refugee camp, had bruised ribs, arms and legs that he said he received from a beating by soldiers. Another patient from the village of Halhoul was in critical condition with a gunshot wound in the chest. An Army spokesman said he was checking what had happened there.

There were four other gunshot wound victims from Beit Fajr, a village north of Hebron that had been peaceful until this morning. Soldiers arrived there after a mob burned a local bus that carries workers to jobs in Israel. The Army had no report on the incident.

"We had quite a few cases today where we got in touch with Israeli hospitals and they refused to take them," said Dr. Abdeen.

Abdeen and Nammari also charged that Jerusalem police had summoned the hospital's sole ambulance to the village of Jebel Mukabar where stone throwers were holding them off after stoning Jewish houses in nearby East Talpiot. When the vehicle arrived, they said, a dozen police commandeered it, ordered out the driver and two attending physicians and drove into the village to assault the rioters. The police then returned the ambulance but ordered the crew to leave the area without evacuating any of the wounded, Abdeen and Nammari said.

"It was a trick by the police from the beginning and we are very angry about it," said Nammari, chief of the hospital's orthopedics department. A police spokesman could not be reached for comment.

City bulldozers came to Mukabar this afternoon and dumped large boulders and dirt on the two roads leading to East Talpiot from the village. City officials said the move was designed to deter further incidents like the one this morning. Residents said buses and cars would have to use a back route that would add several miles to their journey to the city.

In renewed violence in predominantly Arab East Jerusalem, people shattered street lights in Sawahra and smashed city water pipes at their joints in Anata and Abu Tor. Officials said they may have to turn off water to some neighborhoods for as long as a week to repair the damage.

When a curfew was last imposed on an Arab neighborhood Jan. 22, Jerusalem Mayor Teddy Kollek registered a strong protest, saying the move unnecessarily damaged the city's image as a haven of relative peace. This time, however, he acceded without objection.

"It just goes to show that a few boys with a few telephone tokens in their pockets can start a revolution," he said.

Trouble also hit the Gaza Strip today. There was a near-total strike in the area after leaflets warned residents to stay off the streets. A 20-year-old man from Khan Yunis was shot in the thigh during a disturbance, and U.N. officials said 37 residents had been treated for beating injuries at the U.N. health clinic in the Jabaliya refugee camp after an Army raid there.

Defense Minister Yitzhak Rabin, Police Minister Haim Bar-Lev and Army Chief of Staff Gen. Dan Shomron painted a gloomy picture of the violence at a Cabinet meeting this morning.