Israeli security forces arrested four Palestinians and searched 120 buildings in the Hebron area overnight Monday as part of Israel’s ongoing efforts to find three teens who were kidnapped on June 12.

Since the start of operation “Brother’s Keeper,” the large-scale IDF action in the West Bank aimed at returning the three and weakening the power base of the Islamist group Hamas, which Jerusalem says is behind the kidnapping, Israel has searched some 1,800 locations and arrested 354 Palestinians, the army said. Of these, 269 were Hamas members and 57 were among those were released as part of the 2011 deal to free captured soldier Gilad Shalit.

A senior military official said Tuesday that beginning next week, a judicial committee would review some of the cases of those who have been recaptured after being released under the Shalit deal, to see if they would be re-imprisoned to serve out their original sentences.

Over the course of the operation, in clashes with Israeli forces, four Palestinians have been killed, including a 14-year old boy, and one 60-year-old man died after suffering a heart attack while protesting a IDF search of his home.

Tony Blair, the Middle East Quartet’s special envoy to the region, said Tuesday that he was “deeply troubled by the ongoing events in Israel and the Palestinian territories, including the deaths of Palestinian civilians, and the wide-scale arrests.”

Blair called on Israel to “act with restraint” during the effort to find the kidnapped teens, and “ensure that civilians are not harmed. Steps must also be taken to limit restrictions on movement and access in the West Bank.”

Blair, a former British prime minister, welcomed PA President Mahmoud Abbas’s condemnation of what Blair called the “heinous” kidnapping and said that “the international community utterly condemns the kidnapping of three Israeli teenagers and calls for their immediate and unconditional release.”

On Monday, the IDF said that the kidnappers may be waiting to take responsibility for the act because they have yet to arrive at their final destination. Movement in and out of the city of Hebron, where IDF searches are focused, has been extremely restricted over the past 12 days. Over a thousand soldiers have scoured the area in intensive searches for the three kidnapped youths, alongside nightly raids.

The three youths — Eyal Yifrach, 19, Gil-ad Shaar, 16, and Naftali Fraenkel, 16 — were abducted on June 12 while hitchhiking at a bus stop in the Etzion settlement bloc south of Jerusalem. An emergency call to the local 911 number, in which one of the teens whispered that they had been kidnapped, went unheeded for hours.

Over the ensuing days, nine brigades have been deployed to the West Bank. Since Friday, the IDF has narrowed its focus to the Hebron region, with company commanders receiving maps of wells, caves, and stone terraces that the troops are tasked with searching.

Times of Israel staff contributed to this report.