Israeli troops continued their hunt for the prime suspects in the kidnappings and murders of three Israeli teenagers overnight Monday and into Tuesday, sealing off the West Bank city of Hebron and the nearby village of Halhul.

Military sources said early Tuesday they believe the killers of the teens are still in the Hebron area.

The bodies of Naftali Fraenkel, Eyal Yifrach and Gil-ad Shaar were found in Halhul on Monday afternoon, after an 18-day search for the three teens who were kidnapped from a hitchhiking post in the Etzion Bloc on June 12.

The two Hamas men Israel believes carried out the abduction and murders, Amer Abu Aysha and Marwan Kawasme, have been missing from their homes in Hebron’s Hares neighborhood ever since the kidnapping took place. They were allegedly in the car in which the three were abducted.

The two were still at large Tuesday, and Israel’s security forces were making intensive efforts to track them down. Three Palestinians were arrested overnight Monday in the West Bank.

In Jenin, a Palestinian was shot dead after he threw a grenade at troops, a senior military official said Tuesday morning. The official said that the IDF had arrested 419 Palestinians since the onset of the operation, and that 57 of them had been released under the 2011 deal that saw abducted soldier Gilad Shalit freed. Soldiers had searched more than 2,200 sites, the official said.

Later Monday night, Israeli forces blew off the doors at the family home of Marwan Kawasme, one of the two Hamas members alleged by Israel to have carried out the killings. Military sources said earlier reports that the home was demolished were incorrect.

Hamas officials in Hebron confirmed the two suspects were members, and said Israeli troops had targeted the men’s homes since the beginning of Operation Brother’s Keeper. The officials said troops had entered the homes several times, conducting intense searches and confiscating items as evidence.

Since the start of Operation Brother’s Keeper to find them, 18 days of searches had seen the arrests of over 400 Palestinians, a majority of them members of Hamas.

Netanyahu vowed Monday night that “Hamas will pay” for the murders of the three Israeli teenagers, who were kidnapped on June 12.

Netanyahu said it was “with great sorrow that we found the three bodies” — of Fraenkel, 16,Shaar, 16, and Yifrach, 19 — who he said were “kidnapped and murdered in cold blood by animals… Hamas is responsible and Hamas will pay,” he said.

Early Tuesday morning, the Israeli Air Force struck 34 targets in the Gaza Strip in response to ongoing rocket fire from the Palestinian enclave.

A senior military official said early Tuesday that Hamas bore “clear responsibility” for recent rocket fire emanating from the Gaza Strip. He said that he scope of the airstrikes on Gaza overnight were intended to “convey that message.”

The bodies of the three teens were found at about 5:30 p.m Monday, bound and partially buried, in an open field in a hard-to-access area known as Wadi Tellem near Halhul. The site is less than 20 kilometers (12 miles) from where the teens had been abducted.

Fraenkel, Shaar, and Yifrach were kidnapped on the night of June 12 at a hitchhiking post outside the settlement of Alon Shvut in the Etzion Bloc south of Jerusalem. “They were on their way to home to be with their parents,” said Netanyahu bitterly, “but will not see them again.”

Netanyahu telephoned the families and expressed his condolences. “The entire nation is crying as one,” he said.

The three Israeli teenagers had been killed soon after their abduction, and the bodies were apparently disposed of hurriedly. The bodies were not in a good condition when they were found, Channel 2 said. “It was a harrowing sight.”

Forensic experts identified the bodies at the scene. The bodies were flown to the Abu Kabir Institute for Forensic Medicine in Tel Aviv on Monday evening for definitive identification. Israelis placed mourning candles outside the institute later Monday night.

The funerals were set to be held later Tuesday.