GEOFF BENNETT: There was more violence today in the occupied West Bank, as Israeli settlers were shot and killed by Palestinian gunmen.

It followed a bloody raid by Israeli forces yesterday in the Northern West Bank and is raising fears of escalation.

Here's Stephanie Sy.

STEPHANIE SY: Near the Israeli settlement of Eli in the occupied West Bank, Palestinian attackers gunned down four Israeli settlers at a gas station.

According to an Israeli newspaper, three of the victims were young men 21 and under.

The fourth victim was 63.

Four others were injured.

Both gunmen were also killed, one by an armed civilian, the second by Israeli forces.

Prime Minister Benjamin Netanyahu called the assailants murderers.

BENJAMIN NETANYAHU, Israeli Prime Minister (through translator): I want to say to all those who seek our souls, all options are open.

STEPHANIE SY: Hamas said the gunmen were embers who carried out the attack in retaliation for a deadly Israeli raid in the Jenin refugee camp yesterday.

Palestinians are mourning five people killed in that raid, including 15-year-old Ahmed Saqr, whose family griefs.

What was a routine Israeli raid against suspected Palestinian militants became even more serious as the Israeli troops left.

A roadside bomb exploded under two Israeli military vehicles, an unusual weapon in the West Bank.

Israel deployed a helicopter gunship, the first time in two decades it used an armed helicopter over the area.

SHIBLEY TELHAMI, Anwar Sadat Professor for Peace and Development, University of Maryland: The use of Israeli helicopters firing missiles into the area, and so that is really a huge escalation.

STEPHANIE SY: Shibley Telhami is a senior fellow at the center for Middle East Policy at the Brookings Institution.

He fears that, with today's attack on Israeli settlers, violence could intensify.

Telhami says the recent burst of violence is linked to the expansion of Israeli settlements in the West Bank.

SHIBLEY TELHAMI: We have calls by the Israeli national security minister, who has been from the far right, Ben-Gvir, who has been calling now for very major measures in the West Bank against the Palestinians, including the return of targeted assassinations and -- quote -- "destruction of buildings.

STEPHANIE SY: Telhami says the recent burst of violence is linked to the expansion of Israeli settlements in the West Bank.

SHIBLEY TELHAMI: Palestinians don't see any possibility of ending occupation anytime soon.

So there's a lot of despair.

STEPHANIE SY: Over the weekend, Israel announced a new round of settlement expansion, 4,000 units, just as a top American State Department official was arriving.

From Washington, the State Department issued a four-sentence statement, saying the U.S. was -- quote -- "deeply troubled."

DAVID MAKOVSKY, Senior Fellow, Washington Institute for Near East Policy: It's a perfect storm, whereby you have got you have got a vacuum in the West Bank filled by militant groups, and you have a government in Israel that has elements to it that would like to not just have no two states, but preclude it ever happening in the future.

STEPHANIE SY: David Makovsky is the director of the Koret Project at Arab-Israel relations at the Washington Institute.

He says that far right policies in Israel have further weakened the Palestinian Authority.

Earlier this year, Minister of Finance Bezalel Smotrich seized taxes earmarked for the PA. And just this week, Smotrich was given authority for settlement planning in the West Bank.

DAVID MAKOVSKY: The finance minister in Israel, Mr. Smotrich, who represents more of the hard-line factions, he has not been providing the support that the security establishment wants to bolster the PA. Clearly, the more they're vacuums in governance, the more it gives space for these groups, these terror groups, to operate.

STEPHANIE SY: Meanwhile, settlers are taking matters into their own hands, with reports of revenge attacks against Palestinians mounting tonight.

For the "PBS NewsHour," I'm Stephanie Sy.