Paris: Countries around the world have condemned a wave of Palestinian attacks by land, sea and air that Israel's army says left more than 200 dead.
Some countries also called for a de-escalation of the conflict, after Israel launched air strikes and other military operations targeting Gaza that Palestinian authorities say killed more than 230 people.
"We are at war," Israel's Prime Minister Benjamin Netanyahu said when he vowed severe retaliation after Hamas's surprise assault.
Here is a roundup of the reactions:
President Joe Biden said US support for Israel was "rock solid and unwavering".
"The United States stands with Israel," Biden said in a televised statement at the White House, flanked by US Secretary of State Antony Blinken.
"We will not ever fail to have their back."
A White House official said talks with Israel on military aid were "very much underway".
Saudi Arabia's foreign ministry said: "The Kingdom calls for an immediate halt to the escalation between the two sides, protection of civilians, and self-control".
"The Kingdom is reminded of its repeated warnings of the dangers of an explosive situation as a result of the continued occupation and deprivation of the Palestinian people of their legitimate rights," it added.
The UN's human rights chief Volker Turk said: "I call for an immediate stop to the violence, and appeal to all sides and key countries in the region to de-escalate to avoid further bloodshed."
He said he was "deeply concerned at reports that Israeli civilians have been taken hostage".
EU chief Ursula von der Leyen said: "I unequivocally condemn the attack carried out by Hamas terrorists against Israel."
"It is terrorism in its most despicable form. Israel has the right to defend itself against such heinous attacks," she said.
EU foreign policy chief Josep Borrell said "this horrific violence must stop immediately. Terrorism and violence solve nothing. The EU expresses its solidarity with Israel in these difficult moments."
He added: "News of civilians taken as hostages in their homes or to Gaza are appalling. This is against international law. Hostages must be released immediately".
Brazil, which holds the UN Security Council presidency, condemned the attacks on Israel.
A statement from its foreign ministry urged "all parties to exercise maximum restraint in order to avoid escalating the situation".
Shortly after, it said it would call an emergency UN Security Council meeting on the crisis. The Council announced they would meet Sunday.
China said it was "deeply concerned" by the weekend's dramatic escalation of violence between Israel and the Palestinians, urging all sides to show "calm".
"China is deeply concerned about the current escalation of tension and violence between Palestine and Israel," Beijing's foreign ministry said, adding it "calls on all parties concerned to remain calm and exercise restraint, cease fire immediately, protect civilians and prevent further deterioration of the situation".
Russia's foreign ministry called for an "immediate ceasefire".
"We call on the Palestinian and Israeli sides to immediately cease fire, renounce violence, show the necessary restraint and - with the help of the international community - establish a negotiation process aimed at establishing a comprehensive, lasting and long-awaited peace," ministry spokeswoman Maria Zakharova said.
Ukrainian President Volodymyr Zelensky, whose country is fending off a Russian invasion, said Israel had an "indisputable" right to defend itself.
"Terror is always a crime, not just against one country or specific victims, but against humanity as a whole," he said.
Turkish President Recep Tayyip Erdogan urged Israel and Palestinians to avoid further escalation.
"We invite all parties to act reasonably and to stay away from impulsive steps that raise tensions," said Erdogan, who strongly supports the Palestinian cause.
France expressed "full solidarity with Israel and the victims" and underscored "its absolute rejection of terrorism and its commitment to Israel's security".
President Emmanuel Macron said he "firmly condemns" the attacks.
German Foreign Minister Annalena Baerbock said Israel "has our full solidarity" and "the right, guaranteed by international law, to defend itself against terrorism".
British Prime Minister Rishi Sunak said he was "shocked" by the attacks.
"Israel has an absolute right to defend itself," he said.
He went further in a post later on X, formerly known as Twitter.
"As the barbarity of today's atrocities becomes clearer, we stand unequivocally with Israel," he wrote.
"This attack by Hamas is cowardly and depraved."
Japan "strongly condemns" the cross-border attacks, foreign minister Yoko Kamikawa said.
Tokyo also criticised the kidnapping of a number of Israelis, including several civilians, she said in a statement.
"Meanwhile, we are seriously concerned about the large number of casualties in the Gaza Strip as a result of attacks by the Israel Defence Forces," her statement continued.
"Japan once again calls on all parties to exercise the utmost restraint to prevent further damage."
South Africa's foreign ministry expressed its "grave concern over the recent devastating escalation in the Israeli-Palestinian conflict".
"The region is in desperate need of a credible peace process that delivers on the calls of a plethora of previous UN resolutions for a two-state solution and a just and comprehensive peace between Israel and Palestine," it added.
Indian Prime Minister Narendra Modi said his country stood "in solidarity with Israel at this difficult hour".
"Deeply shocked by the news of terrorist attacks in Israel," Modi said.
Venezuela's government expressed its "deep concern" over the clashes.
In a statement on X, formerly Twitter, it said the fighting was "the result of the impossibility of the Palestinian people to find in multilateral international legality a space to assert their historic rights".