Israel has vowed to exact harsh retaliation for a Palestinian attack that killed four rabbis in an assault on a synagogue in Jerusalem.
The attack during morning prayers in the west Jerusalem neighbourhood of Har Nof was carried out by two Palestinian cousins wielding meat cleavers, knives and a handgun. They were shot dead by police after the deadliest assault in the holy city since 2008.
Three of the dead were born in the United States and the fourth was born in England, although all held dual Israeli citizenship. Six others were wounded, including two police officers.
Palestinian President Mahmoud Abbas condemned the attack, the first time he has done so in the wave of deadly violence against Israelis. But he also called for an end to Israeli "provocations" surrounding Jerusalem's shrines that are sacred to both Muslims and Jews.
US President Barack Obama called the attack "horrific" and without justification, urging cooperation from both sides to ease tensions and adding that too many Israelis and Palestinians have died in recent months,
The attack, however, appeared to mark a turning point, with the gruesome scene in a house of worship shocking a nation long accustomed to violence.
The government released a photo of a bloody meat cleaver it said came from the crime scene. Government video showed blood-soaked prayer books and prayer shawls on the floor of the synagogue. A pair of glasses lay under a table dripping in blood, and thick streaks of blood lined the floor.
"I saw people lying on the floor, blood everywhere," said Yosef Posternak, who was at the synagogue.
"People were trying to fight with (the attackers) but they didn't have much of a chance," he told Israel Radio.
In one of Israel's first acts of retaliation, Prime Minister Benjamin Netanyahu ordered the demolition of the homes of the attackers. But halting further violence could prove to be a tough challenge as police confront a new threat - lightly armed assailants from annexed east Jerusalem who hold residency rights that allow them to move freely throughout the country.
Mr Netanyahu condemned the deaths of "four innocent and pure Jews." In a nationally televised address, he accused Mr Abbas of inciting the recent violence and said the Palestinian leader's condemnation of the attack was insufficient.
Hamas, the militant Palestinian group that runs the Gaza Strip, praised the attack. In Gaza, dozens celebrated in the streets.
The US-born victims were identified as Moshe Twersky, 59, Aryeh Kupinsky, 43, and Kalman Levine, 55. The Israeli Foreign Ministry said the British man was Avraham Goldberg, 68, who immigrated to Israel in 1993.
Mr Twersky, a native of Boston, was the head of the Toras Moshe Yeshiva, a seminary for English-speaking students. He was the son of Rabbi Isador Twersky, founder of Harvard University's Centre for Jewish Studies, and a grandson of Rabbi Joseph B Soloveitchik, a luminary in the world of modern Orthodox Jewry.
All four lived on the same street. Thousands of people attended a joint funeral for Kupinsky, Levine and Goldberg before sundown- held outside the synagogue where they were killed.
IT onight, several hundred Jewish youths marched through Jerusalem, blocking traffic and chanting, "Death to Arabs." Police reported at least 10 arrests.
Police identified the synagogue attackers as Ghassan and Oday Abu Jamal, cousins from the Jabal Mukaber neighbourhood in east Jerusalem.
Police spokesman Micky Rosenfeld said the assailants were killed in a shootout with police that left one officer critically wounded. He said police were still trying to determine how the men had chosen their target.
Mohammed Zahaikeh, a social activist in Jabal Mukaber, said he did not know whether the cousins were politically active. He said Ghassan was 27, married with two young children and worked in a clothing store. Oday, 21, was not married and was an interior decorator. He said both men were quiet, and residents were surprised by the attack.
Clashes later broke out outside the assailants' home, where dozens of police officers had converged. Residents hurled stones at police, who responded with tear gas and stun grenades. Residents said 14 members of the Abu Jamal family were arrested.
The violence has created a special security challenge for Israel. Where Palestinian violence has traditionally been carried out by organized militant groups based in the West Bank or Gaza, most of the recent attacks have been done by perpetrators from east Jerusalem acting on their own.
"There is no solution in the world of intelligence to the problem of a lone wolf who decides in the morning to launch an attack in the afternoon," said Cabinet Minister Yaakov Peri, a former director of the Shin Bet internal security agency.
He said the "only solution is very strong deterrence," such as swiftly demolishing the homes of attackers.
Mr Netanyahu has vowed to revive the policy of home demolitions, which Israel halted in 2005 after determining it wasn't an effective deterrent. Israeli officials have reversed their opinion, and Mr Netanyahu has ordered stepped-up demolitions.