Israel's president on Thursday denounced "bloodthirsty Arab mobs" after rioting by Arab-Israelis spread across Israel following lethal exchanges of rocket fire and airstrikes over the Gaza border.
Israel was facing serious unrest in several major cities after pumelling Gaza with airstrikes that killed dozens, including at least 14 Palestinian children.
It came as Hamas rockets rained down on cities including Tel Aviv, killing at least six Israelis and prompting speculation that a third Intifada, or uprising, may be under way.
A state of emergency was declared in the central city of Lod following riots by Arab-Israelis that saw schools, synagogues and cars set ablaze in Jewish neighborhoods.
As the wave of violence spread to cities including Haifa, Acre and Ramla, Hamas militants continued to fire hundreds of rockets and Israel kept bombing the crowded coastal enclave of Gaza.
The death toll was nearly 60 by late Wednesday, including six Israelis and at least 53 Palestinians. Around 15 children, all but one Palestinian, were believed to have died, as well as several top Hamas commanders.
Israeli airstrikes on Gaza were expected to continue on Wednesday night, as Benjamin Netanyahu, the prime minister, warned that the operation was far from over.
Israeli police chiefs were already drawing comparisons on Wednesday between the riots and severe unrest in 2000 that heralded the Second Intifada, a mass Palestinian uprising against the Jewish state that lasted for five years.
In Lod, a city with a significant Arab Israeli population, Jewish families on Wednesday morning were clearing debris from the fire-ravaged interior of a local school as the stench of burned rubber and plastic wafted through the air.
The building had been attacked with Molotov cocktails by a group of around 30 masked Arabs, according to Jewish families in the area.
"I am a former soldier, I was not scared then, but when I looked out the window I knew that if I went outside I would be killed," Yedidya Harris, a 28-year-old father-of-two, told The Telegraph.
At least a dozen cars, a synagogue and a school were torched during the riots overnight Tuesday.
"The sight of the pogroms in Lod and the disturbances across the country by an incited and bloodthirsty Arab mob, injuring people, damaging property and even attacking sacred Jewish spaces is unforgivable," Reuven Rivlin, the president of Israel, said in an unusually strong statement on Wednesday.
"We have not seen this kind of violence since October 2000," Israeli police chief Kobi Shabtai said of Lod, referring to Arab unrest that preceded the Second Intifiada.
During a visit to Lod on Wednesday, Benjamin Netanyahu, the prime minister, said: "We will not tolerate this; we need to restore calm. If this isn't an emergency situation, I don't know what is. We are talking about life and death here."
Some Palestinian residents in the neighbourhood blamed much of the violence on Israeli settlers who they claimed had disguised themselves as Arabs.
"These are Palestinian cars," said Mohammed, 30, as he pointed to a row of torched vehicles in Lod. "The settlers came dressed as Arabs and burned the cars."
Separately in Acre, a coastal city famed for its status as a Templar stronghold during the Crusades, the popular Jewish-owned restaurant Uri-Buri was set ablaze.
The nationwide unrest was spurred on by ongoing fighting between militants in Gaza and Israel.
Israel announced on Wednesday that it had destroyed weapons manufacturing sites used by Hamas and Islamic Jihad, another militant group in the Gaza Strip.
It also said a separate strike had killed several high-ranking Hamas commanders, including the head of the Gaza City military division, Bassem Issa. His death was confirmed by Hamas.
Israel carried out hundreds of strikes targeting Hamas in response to an unprecedented barrage of 130 rockets that were fired from Gaza at Tel Aviv and the surrounding area on Wednesday.
As of Wednesday evening, Palestinian officials said the death toll had reached 53, including 14 children, while at least 300 had been injured.
Gazans who posted footage online of huge explosions in urban areas, as plumes of smoke rose over the city. Many people had to be rescued from the remains of smouldering buildings.
Five members of a single family were killed in an airstrike on Tuesday, it emerged.
"We were laughing and having fun when suddenly they began to bomb us. Everything around us caught fire," said a relative, Ibrahim, 14.
"I saw my cousins set alight and torn to pieces," he said as he broke down in tears.
Israel saw six casualties from Hamas rocket fire that killed one woman in a suburb south of Tel Aviv, two women in the southern city of Ashdod, and two people in Lod.
In the Tel Aviv suburb, Rishon LeZion, the victim's house had been caved in by a rocket that set several cars in the street ablaze.
Residents told The Telegraph the rocket launch had led to a second casualty in their neighbourhood, as a woman died from a heart attack during the barrage.
Konstantin Kandaurov, a 48-year-old software engineer, said he was watching a football match in his living room when he heard the sirens screaming.
"As soon as the explosion [happened] the cars started burning," he said, adding that it was his first experience of a rocket attack.
The Israeli military said that more than a thousand rockets had been fired by Hamas towards Israel since their operation against Hamas, Guardians of the Wall, began on Monday.
The operation was triggered by a Hamas rocket launch on Jerusalem on Monday.
Hamas said that was partly in retaliation for hundreds of Palestinians being injured during clashes with Israeli police at the revered al-Aqsa mosque in East Jerusalem.
Another factor that escalated tensions was an Israeli plan to evict around a dozen Palestinian families from their homes in Sheikh Jarrah, and replace them with settlers.
A court hearing due to take place on Monday was postponed after the al-Aqsa clashes. A new date will be set in the coming weeks.
In a statement on Twitter, Boris Johnson called on both sides to "step back from the brink" and to "show restraint."
"The UK is deeply concerned by the growing violence and civilian casualties and we want to see an urgent de-escalation of tensions," he said.
US Secretary of State Antony Blinken on Wednesday reiterated his urging for a halt to violence in a call with Prime Minister Benjamin Netanyahu.
"The secretary reiterated his call on all parties to de-escalate tensions and bring a halt to the violence," said a State Department statement.
"The secretary emphasised the need for Israelis and Palestinians to be able to live in safety and security."
Joe Biden, the US president, has so far not spoken out directly on the matter.
The chief prosecutor of the International Criminal Court also voiced concern at the escalation of violence between Israel and the Palestinians and said "crimes" may have been committed.
"I note with great concern the escalation of violence in the West Bank, including East Jerusalem, as well as in and around Gaza, and the possible commission of crimes under the Rome Statute," which founded the ICC, Fatou Bensouda said on Twitter Wednesday.
In Russia, president Vladimir Putin said the world needed to give Israel a "strong" lesson.
"Serious concern was expressed about the continuing clashes and the growing number of people killed and wounded," the Kremlin said in a statement.
And in Germany, Chancellor Angela Merkel's spokesman Steffen Seibert said her government "condemns these incessant rocket attacks from the Gaza Strip against Israeli cities in the strongest terms", saying they "could not be justified".
"Israel has the right to self-defence against these attacks," he said.