The IDF early Sunday closed the area around Hebron and the crossings into the Gaza Strip as security forces searched intensively for three teenagers kidnapped late Thursday night from the Gush Etzion region of the West Bank. The Gaza crossings will only be opened for humanitarian reasons, such as medical emergencies.The Shin Bet (Israel Security Agency), Defense Minister Moshe Ya’alon ordered the closures after a Security Cabinet meeting late Saturday night.Prior to the meeting Prime Minister Binyamin Netanyahu said he had ordered the IDF “to prevent the possibility of their [the teens] being moved to the Gaza Strip or any other place.He also ordered the security services to use all means at its disposal to locate the captives and to prepare all forces for any scenario.IDF Chief of Staff Lt.-Gen. Benny Gantz said the military would expand the scope of its operations to retrieve the abducted youths while keeping an eye on Gaza and the northern arena.The IDF has carried out house-to-house searches, round-ups and interrogations in Hebron and its outlying villages. They arrested at least 12 Hebron-area residents, including two women, confiscated videos from privately owned security cameras and prevented around 300 residents from leaving the area, Palestinian officials and witnesses said.Security forces are investigating a burned-out car found in the south Mount Hebron area on Friday due to suspicions that it was used to transport the kidnapped youths on Friday. Crime-scene forensic examiners from the Judea and Samaria district are testing the car.Two of the missing teens, Gilad Sha’ar, 16, from the West Bank settlement of Talmon, and Naftali Frankel, 16, from Nof Ayalon near Latrun, are friends and study together at the Makor Chaim Yeshiva in the Kfar Eztion settlement. Frankel has dual Israeli-American citizenship.The third teen, Eyal Yifrach, 19, from Elad, near Petah Tikva, studies in the Shavei Hevron Yeshiva in Hebron.The three teens caught a ride from a hitchhiking post in Gush Etzion on Thursday night. They called or sent SMS text messages to their parents, telling them they were heading home. They never arrived.From the Western Wall in Jerusalem to the Cave of the Patriarchs in Hebron, thousands of people held prayer services late Saturday night and early Sunday morning for the safe return of the three captive teens. Worshipers also gathered at the Nokdim junction in the West Bank and at the Makor Chiam yeshiva where two of the teens studied. In the last two days, Gantz, OC Central Command Maj.-Gen. Nitzan Alon, representatives of the intelligence community, territorial brigade commanders and the police held multiple consultations, as did Netanyahu and Ya’alon.The IDF and Shin Bet (Israel Security Agency) arrested a number of Palestinians overnight in Judea, a defense source stated, as part of an effort “to get closer to the inner circle [of the terrorist cell] that handled the teenagers who disappeared.”“We are checking a number of directions,” the source continued, warning that the search could span days rather than hours.“All of our operational and intelligence systems have been very much involved in the past 24 hours to try and retrieve the teenagers,” he said.On Saturday, the IDF deployed all the battalions of the 35th Paratroopers Brigade to the West Bank, as well as a number of special forces, said the defense official.In their intensive quest to locate intelligence leads, the Shin Bet and military intelligence are encountering a lot of “background interference,” the official said, and the agencies are making a “highly calculated intelligence effort” to filter out irrelevant or false information.“Our goal now is to move forward and have the Shin Bet and military intelligence direct the units on the ground,” he added.While it seems likely that the youths were seized to enable the release of Palestinian security prisoners, another scenario is also under investigation, the source said, without giving further details.Addressing the possibility that the youths were smuggled out of the West Bank, he said that security forces had not ruled that out.“The [terrorist] organizations [in the West Bank] are well known to us. We know how they work. The investigation is still at the basic level, but it is getting deeper,” said the source.The identities of the kidnappers have not yet been established by the intelligence community and could range from Salafi jihadists, who claimed responsibility on Friday, to Hamas.Security coordination with the Palestinian Authority has remained good since the start of the crisis.“The PA’s security forces understand the significance of this incident,” he said.Beginning Saturday evening, police went on high alert across the country “in order to prevent incidents of incitement, provocation and disturbances from all sides,” according to National Police spokesman Rafi Yafeh. He also said they had canceled a national training drill scheduled to begin on Sunday and that National Police Commissioner Yochanan Danino, currently attending a conference in the United States, had cut his trip short in order to return to oversee the police efforts.The Israel Prison Service is also wary of possible disturbances among security prisoners, but as of Saturday afternoon said there had been no rioting, violence or celebrations,on the part of the Palestinian security prisoners.Reuters contributed to this report.