An undisclosed number of suspects were arrested on late Friday night raids in Nablus, on suspicion of being linked to Thursday’s deadly shooting attack in which terrorists murdered Eitam and Naama Henkin as they drove in their car near Itamar.The arrests were carried out by the Shin Bet domestic intelligence agency together with the IDF, Israel Police, Duvdevan special operations unit, and the Border Police’s Counter-Terrorism Unit. The forces moved into the Palestinian city, located some five kilometers northwest of the scene of the murders, and made several arrests of security suspects.“In the past 24 hours, there has been a significant development in the investigation,” the Shin Bet announced on Saturday evening. “The investigation continues and a media ban is in place on all other details of the investigation,” it added.The IDF has deployed four additional battalions to the West Bank to take part in the search for the terrorist cell and to respond to the deteriorating security situation.On Friday, Defense Minister Moshe Ya’alon said large numbers of security personnel are operating in Judea and Samaria to capture the perpetrators, who gunned down the parents in front of their four children.Ya’alon visited the scene of the shooting, near Itamar, and received briefings from IDF senior commanders and intelligence officials.He was accompanied by IDF Chief of Staff Lt.-Gen. Gadi Eisenkot, and Shin Bet chief Yoram Cohen.“We are here on the ground with many forces that are operating – the IDF and the Shin Bet – to place our hands on the murderers,” Ya’alon said.“Sooner, I hope, and not later, we will place our hands on them, as we have done in past incidents. There is no doubt that this is a most severe incident.This is how we are treating it, and the actions on the ground are designed to prevent the next attack,” he said.The current period is marked by an “eruption,” Ya’alon stated, adding that “this is, and is not, linked to the Temple Mount. It is unfortunately being accompanied by incitement from the Palestinian authority, particularly, from the head of the Palestinian Authority.”The violent atmosphere “leads to murders and the spilling of blood. Hence, we are acting against those who are responsible for the incitement, and I hope we are able to stabilize the security situation soon.”IDF units are beefing up their presence in Judea and Samaria in order to provide a solution to these types of attacks, Ya’alon said. The forces are there to stop rock throwing attacks and firebombings, as well as shootings, according to the defense minister.“I hope that this extensive activity will lead to a calming of the security situation on the ground,” he said.Late Thursday night, suspected far right activists torched a Palestinian vehicle in the village of Beitilu, near Ramallah, and spray-painted the words “revenge Henkin” on a Palestinian home. The Judea and Samaria Nationalist Crimes Department is investigating.Referring to the retaliatory attack, Ya’alon issued a call to the settler leaders and to residents of Judea and Samaria to “act responsibly.”“Violent acts like those that occurred yesterday are disruptive, also to the IDF, and they add fuel to the fire,” he said.The defense minister received briefings from the head of Operations Branch, Maj.-Gen.Nitzan Alon, OC Central Command Maj.-Gen. Roni Numa, OC Judea and Samaria Division Brig.-Gen. Lior Carmeli, Civil Administration head Brig.- Gen. David Menachem, and the commander of the Samaria territorial brigade, Col. Shai Kleper.The IDF ordered four battalions to join existing military forces in the West Bank on Thursday following the terrorist attack. The first of the extra units began arriving on Friday.The main focus of this stage of the defense establishment’s response will be on the intelligence front, a senior IDF officer said. “There is certainly a change of atmosphere on the ground,” he added.Additionally, the IDF surrounded a number of Palestinian villages in the vicinity of the attack to help the hunt for the terrorists.Ben Hartman contributed to this report.