Israeli Prime Minister Benjamin Netanyahu said Saturday that three teenage students who went missing in the West Bank on Thursday night were “kidnapped by a terrorist organization,” and he said Israel would hold the Palestinian government accountable.

Netanyahu, speaking in a nationally televised address, did not blame the Palestinian Authority for the kidnapping of three teens, but said he would hold it “responsible for any attack coming from its territory.”

Netanyahu’s comments came as Israeli forces deployed more soldiers and intelligence agents to the West Bank on Saturday in an intensive search for the teens, all students at a religious school, or yeshiva. One of them, Naftali Frankel, 16, is a dual Israeli-American citizen.

Investigators are working under the theory that Frankel and the other teens, ages 16 and 19, were hitchhiking when they disappeared Thursday night outside the city of Hebron near the Jewish settlement cluster of Gush Etzion, in part of the occupied West Bank called Area C that is controlled by the Israeli military.

A senior Palestinian official, who spoke on the condition of anonymity because his statements needed to be cleared in advance, said, “It is not we who failed to have our police present. We are forbidden from providing any police, any security in Area C.”

A senior Israeli military officer said there have been dozens of kidnapping attempts of Israelis, including soldiers, in the past two years, adding that the abductors’ goal has been to trade hostages for Palestinian prisoners.

The officer, who briefed reporters on the ongoing investigation on the condition that he not be identified, said investigators had made “a few tens” of arrests in connection with the case. A paratrooper brigade was brought into the area to assist with the search, he said. Palestinian security forces are cooperating and assisting, said an Israeli military official.

The case of the missing teens has attracted an enormous amount of attention in Israel, where all three television news stations interrupted regular broadcasting and have devoted all coverage since Friday to the story.

Secretary of State John F. Kerry spoke with Israel’s justice minister, Tzipi Livni, and expressed “grave concern” over the missing boys, said a senior State Department official who spoke on the condition of anonymity to brief reporters in Washington.

Kerry also spoke to Palestinian Authority President Mahmoud Abbas “to urge him to do everything possible to assist in the effort to find them. President Abbas assured him that he is doing so,” the U.S. official said.

Netanyahu held an emergency meetings Friday and Saturday with his security staff, including army chief of staff Benny Gantz and Defense Minister Moshe Yaalon.

“As long as we don’t know otherwise, our working assumption is that they are alive,” Yaalon told reporters Saturday. “We will not rest until we free the youths and put our hands on the terrorists who are responsible for this operation.”

Israeli soldiers arrest a Palestinian man in the West Bank City of Hebron, June 14, 2014. Israeli security forces searched the West Bank for a second day Saturday, looking for three missing teenagers, including a U.S. citizen, who they fear have been abducted by Palestinian militants. (Majdi Mohammed/AP)

Israelis have responded to past kidnappings with dramatic moves. The 2006 Lebanon war was sparked when Hezbollah, a Lebanese militant group, captured two Israeli soldiers along the border. In 2011, Israel released more than 1,000 Palestinian prisoners in exchange for Israeli soldier Gilad Shalit, who was abducted and held for five years in the Gaza Strip by the Palestinian militant organization Hamas.

The SITE Intelligence Group, which monitors militant Web sites and activity, reported Saturday that two jihadist groups had posted claims of responsibility for kidnapping the teens.

A group calling itself the West Bank branch of the Islamic State of Iraq and Syria said it had carried out the abduction to avenge the deaths of three fighters. Another group, Brigades of Global Jihad, also posted on a jihadist Web forum, but the communique was deleted, according to SITE.

A third group, Liberators Battalion of Hebron, sent a message to Israeli media claiming responsibility, according to news reports in Israel.

An Israel military officer who spoke on the condition of anonymity because the investigation is ongoing said Saturday that “there are a lot of statements floating around, and they will be evaluated.” But he cautioned that such groups, if they exist, often make claims that turn out to be false.