Deadly Synagogue Attack Horrifies Israel, Netanyahu Says Jerusalem Facing 'Terror' Onslaught

Two Palestinians armed with a gun and meat cleavers burst into a Jerusalem synagogue Tuesday and killed four Israelis before being shot dead in the city's bloodiest attack in years.

It was a rare assault on a place of worship and sent shock waves through the country, raising fears that the Israel-Palestinian conflict was taking on a dangerous religious dimension.

All four victims were Israelis with dual nationality -- three were U.S. citizens and the fourth British, police said. Israel's leading ultra-Orthodox website said all four were rabbis.

Israel vowed a harsh response, with Prime Minister Benjamin Netanyahu calling the bloodshed a "direct result" of incitement by Palestinian President Mahmoud Abbas and Hamas, vowing to respond with "a heavy hand."

Abbas condemned the killings, but Hamas welcomed the attack, with masked Palestinian militants in southern Gaza holding up knives and axes next to posters of the attackers while others handed out cakes in celebration, an AFP correspondent said.

U.S. President Barack Obama called for calm after what he described as a "horrific attack", urging Israelis and Palestinians to work together to "lower tensions, reject violence and seek a path forward towards peace".

The bloodshed took place as months of unrest gripped Jerusalem's annexed Arab eastern sector, resulting in a string of deadly attacks by lone Palestinians and further inflamed by the death of a Palestinian bus driver in controversial circumstances.

But none was as serious as Tuesday's killings at the synagogue in an ultra-Orthodox neighbourhood on the city's western outskirts as worshippers gathered for morning prayers.

As well as the four killed, eight other people were wounded, including two policemen, one of whom was in critical condition, with eyewitnesses saying several people had limbs hacked off.

The attack began shortly before 7:00 am (0500 GMT) when the assailants burst in, waving meat cleavers and a gun at the synagogue in a Jewish seminary in Har Nof.

Three policemen engaged in a gunbattle with the attackers who were shot dead, police spokeswoman Luba Samri said.

The assailants were identified by family members as Uday and Ghassan Abu Jamal, cousins from the east Jerusalem neighbourhood of Jabal Mukaber. Both were in their 20s.

Later on Tuesday, Netanyahu said Israel was facing “the height of an ongoing terror attack focused on Jerusalem."

He warned Israelis against taking the law into their own hands by carrying out revenge attacks, and also pledged to demolish the homes of the assailants who carried out the assault.

"This evening, I ordered the destruction of the houses of the Palestinians who carried out this massacre and to speed up the demolition of those who carried out previous attacks," he said, reiterating a pledge made on November 6 just days after a Palestinian rammed his car into pedestrians, killing two in the second such hit-and-run attack in a fortnight.

But Netanyahu also sought to calm tempers, warning Israelis not to take the law into their own hands.

"Citizen of Israel, I call on you to demonstrate great vigilance and to respect the law because the state will bring to justice all the terrorists and those who dispatch them," he said.

"It is forbidden for anyone to take the law into their own hands, even if tempers are high and even if you're burning with anger."

Israel would also "step up enforcement and harshen the penalties" against anyone or any organization involved in incitement, the premier said.

He linked the attack to statements about the flashpoint al-Aqsa mosque compound made by the Palestinian Authority, the Islamist Hamas movement and Israel's Islamic Movement, a religious advocacy group.

"Hamas, the Islamic Movement and the Palestinian Authority are spreading no end of libels... against the state of Israel," he said.

"They say that the Jews are defiling the Temple Mount, they say that we are planning to destroy the holy places there, that we are intending to change the prayer rites there.

"It's all a lie. And these lies have already cost a very high price," he said, listing the Israeli victims of recent Palestinian attacks in Jerusalem.

"Today more victims were added to their number due to this crazy blood libel," he added.

Analysts warned a harsh Israeli response could potentially escalate a situation already fraught with tension.

"This event has the potential of being a game changer," said Kobi Michael, senior researcher at the Institute for National Security Studies.

Witnesses spoke of a bloodbath.

"There were people running from the synagogue, and a man sitting on the pavement covered in blood," said resident Sarah Abrahams.

"Two people came out with their faces half missing, looking like they'd been attacked with knives," she said as hundreds of ultra-Orthodox Jews pressed up against the police tape, a few chanting "Death to terrorists".

Emergency worker Moti Bukchi said the scene was "harrowing".

"Inside the synagogue some were wounded by gunshots, others had chopped off limbs caused by a meat cleaver," he said.

"We have seen things here for the first time -- a man goes in with a meat cleaver and starts to attack people and chop off their limbs. That is something new," he told AFP.

Speaking to journalists at the scene, Jerusalem Mayor Nir Barkat expressed shock at the brutality of the attack which took place just over a mile (1.5 kilometres) from the Yad Vashem Holocaust museum.

"To slaughter innocent people while they pray... it's insane," he said.

Har Nof is also very close to the former Palestinian village of Deir Yassin where Jewish militias massacred more than 100 villagers in 1948.

A similar attack to Tuesday's took place in March 2008 when a Palestinian gunman killed eight students and wounded 11 at the Mercaz HaRav yeshiva just two kilometres away before being shot dead.

The funerals of the four victims began at dusk at a nearby cemetery.

In Jabal Mukaber, police rounded up the perpetrators' family members, sparking clashes with stone-throwing youths, relatives said. Police confirmed arresting nine people.

Arab east Jerusalem has been a tinderbox since early July when Jewish extremists killed a 16-year-old Palestinian in revenge for the murder of three Jewish teenagers, sparking a wave of violence which has shown no sign of letting up.

Defense Minister Moshe Yaalon vowed Israel would hunt down those who sent the perpetrators "wherever they are and in whatever way necessary, both inside and outside Israel's borders".

And Public Security Minister Yitzhak Aharonovitch pledged to ease controls on carrying weapons for self-defence in a move which would apply to anyone licensed to carry a gun, such as private security guards and off-duty army officers.

U.S. Secretary of State John Kerry condemned the attack as an "act of pure terror and senseless brutality," and called on the Palestinian leadership to denounce it.

But Hamas praised the assault and called for further attacks, saying it was a "response" to Sunday's death of the Palestinian bus driver from east Jerusalem who was found hanged inside his vehicle.

Israeli pathologists ruled out foul play but a Palestinian doctor who attended the autopsy challenged the verdict of suicide, suggesting he had been murdered.