Israeli helicopter gunships and foot soldiers shot and killed two Israeli guards at a remote Jewish outpost in the West Bank today after mistaking them for Palestinian guerrillas trying to stage a sneak attack on a nearby Jewish settlement, Israeli military and police officials said.

The two armed Israelis were at the outpost, recently erected near the city of Hebron, 17 miles south of Jerusalem, to protect an Israeli cell phone antenna and prepare the grounds for settlement expansion, according to an Israeli security source and local officials.

One of the guards was killed when soldiers sprayed his car with at least 200 bullets after it did not stop when soldiers called out. The other was shot by helicopter fire as he was running away just outside the fence of the outpost, a small camp on top of a bald and rocky hill with a shipping container, a trailer and a tall red-and-white antenna.

The two guards, both Israeli citizens, were identified as Yoav Doron, 21, of Jerusalem, and Yehuda Ben-Yosef, 22, of Maaleh Adumim, a large settlement just east of Jerusalem.

"We have been under alert for more than two weeks, warned that terrorists are trying to penetrate here and in Kiryat Arba," another local settlement, said Aharon Egeltal, the rabbi of a religious school in Pnei Haver. "The army is working under great stress and high levels of alert. Their finger is on the trigger, and here comes the thing the army is waiting for, and they did what they did. When the forces are under pressure, these things can happen."

The killings came during a rise in Palestinian attacks against Israeli soldiers and Jewish settlers in and around Hebron, a city with a disputed religious site and a city-center Jewish enclave that has provoked bitter clashes between Jews and Muslims for years. According to the Israeli military, 23 Israeli civilians and soldiers have been killed in six separate Palestinian attacks in the Hebron area in the past four months.

Six days ago, Palestinian gunmen killed a Jewish couple in their home in Kiryat Arba, about four miles north of the site of today's incident, and on Monday an Israeli soldier was killed and two others were wounded in a gun battle with Palestinian militants in the heart of Hebron.

About 200,000 Jewish settlers live in the West Bank and many of the men openly carry weapons. In several recent attacks here and elsewhere, Palestinians have worn Israeli military uniforms, making it increasingly difficult for Israeli soldiers and security officers to determine who is friend and who is foe.

"I can't remember a similar incident . . . but in war, people die from friendly fire all the time," said Ezra Rozenfeld, an official with the council of Jewish settlements in the West Bank and Gaza Strip. "The biggest problem these days is that terrorists are wearing Israeli army uniforms."

Israeli television reported that, before being killed, one of the guards called police to report that Palestinians disguised as soldiers had ambushed him and his partner, mirroring the mistake by Israeli forces who were firing on him.

The killings occurred about 1 p.m. The outpost was built about 12 months ago a mile southwest of Pnei Haver, a small settlement located four miles southeast of Hebron in a rugged, barren area of low grass and terraced farms with almond trees. Israeli military officials said they had "hot alerts of an attack on Pnei Haver," which has about 500 residents, and had beefed up patrols outside the settlement.

According to a statement by the military, soldiers on patrol in the area spotted two armed men, and as they drew near the men, one got into a car and started to drive off. The soldiers "called [on] the vehicle to stop, and once identifying that the driver was armed, the [soldiers] fired shots toward it, killing the driver. On hearing the gunshots, the other armed suspect began running. He was shot and killed by the helicopter."

The small white station wagon, which had foot-long, red signs saying "security" on the hood and both sides and yellow Israeli license plates, was riddled with bullet holes. After soldiers "shouted and waved" for the car to stop and it did not, they evidently concluded they were dealing with Palestinians and opened fire, according to a soldier who arrived later to secure the area.

A guard at a remote outpost was killed after Israeli troops sprayed his car with about 200 bullets. A second guard was killed by fire from a helicopter gunship as he fled on foot. Both were assumed to be Palestinian guerrillas.