Israeli troops locked down the occupied West Bank's most populous city Hebron and surrounding villages on Saturday after two Israelis were killed in Palestinian attacks nearby.
The crackdown comes amid a flare-up in nine months of deadly violence as the end of the Muslim fasting month of Ramadan looms, and after key diplomatic players called for urgent steps by both sides to revive the moribund peace process.
Troops had closed all exit roads from Hebron except for the main northern one, an AFP correspondent reported.
Palestinian security said the army had opened entrances to the villages of Sair and Halhul, but an Israeli military spokeswoman said they had been partially open from the beginning.
The army on Friday said it would also deploy two additional battalions to the area.
The measures were described as the "most substantial steps on the ground" since 2014, when Israeli forces carried out a huge search operation in the southern West Bank for three young hitchhikers abducted and later found murdered by Palestinian militants.
At least 214 Palestinians, 34 Israelis, two Americans, an Eritrean and a Sudanese have been killed in a wave of violence that has rocked Israel and the Palestinian territories since October.
The army has said that around 80 of the attacks on Israelis have been carried out by Palestinians from the Hebron area.
Several hundred Jewish settlers live in a tightly guarded enclave in the heart of the city of more than 200,000 Palestinians, a persistent source of tensions.
On Thursday, 19-year-old Palestinian Mohammed Nasser Tarayra broke into the Jewish settlement of Kiryat Arba on the outskirts of Hebron and killed 13-year-old Israeli-American Hallel Yaffa Ariel in her bedroom before being shot dead by a security guard.
On Friday, 48-year-old Michael Mark was killed after his car was fired on by a suspected Palestinian gunman south of Hebron.
The army was conducting searches for the gunman on Saturday.
An army spokesman said the closure was "intended to break the chain of lethal attacks."
"The physical presence will also disrupt, prevent and foil additional attacks, inspired by the attackers of the last 48 hours," Lieutenant Colonel Peter Lerner told AFP.
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Prime Minister Benjamin Netanyahu was to convene the security cabinet late Saturday following the latest violence, an Israeli official said.
- Facebook's 'responsibility' -
On Friday, Sarah Tarayra, 27, was shot dead after drawing a knife on Israeli forces in Hebron. She was a relative of the Kiryat Arba attacker, and both were from Bani Naim, a village just outside Hebron.
Lerner said the army had revoked the Israeli work permits of all residents of the village.
Internal Security Minister Gilad Erdan meanwhile said Facebook bore "some responsibility" for the Palestinian violence.
Erdan told Channel 2 television that all the "discourse, incitemement and lies" of young Palestinians before deadly attacks take place "happens on Facebook's platform."
He accused Facebook of "sabotaging" the work of the Israeli police by not removing content from West Bank users, and called on the Internet giant to "monitor" its content.
In a report released Friday, the Middle East diplomatic Quartet said Israel's expansion of Jewish settlements in the Palestinian territories was "steadily eroding the viability of the two-state solution".
The Quartet -- comprising of the European Union, Russia, the United Nations and the United States -- called on Israel to halt its demolition of Palestinian homes and confiscation of Palestinian land.
But it also urged the Palestinian Authority to act "to cease incitement to violence and strengthen ongoing efforts to combat terrorism, including by clearly condemning all acts of terrorism".
The Quartet's recommendations are to serve as the basis for push to revive the Middle East peace process which has been comatose since US-brokered talks collapsed in April 2014.
The group also said the Palestinian Authority's lack of control over the Gaza Strip, which is run by the Islamists of Hamas, was another major obstacle to peace.
A rocket launched from Gaza hit the southern Israeli city of Sderot on Friday, causing damage to a building but no casualties.
Israel responded with air strikes early on Saturday against four facilities run by Hamas and the smaller Islamic Jihad militant group. They were empty at the time and there were no reports of casualties.