Gun battles raged Sunday between Hamas militants and Israeli forces a day after the Islamist group launched a surprise attack on Israel from Gaza, in a dramatic escalation of the Israel-Palestinian conflict.

Hundreds of people have been killed on both sides since the Iran-backed Hamas launched the multi-pronged assault at dawn on Saturday, with Israeli forces fighting holdout militants and pounding the Gaza Strip with air strikes.

This is what we know about the conflict so far:

How it unfolded

The army said hundreds of Hamas militants attacked Israel from around 6:30 am (0330 GMT) on Saturday, the Jewish holiday of Simchat Torah, in an assault that also came 50 years after the outbreak of the 1973 Arab-Israeli war.

The Islamist group fired thousands of rockets into Israel from Gaza as its militants used explosives and bulldozers to break through the fence surrounding the blockaded Palestinian enclave.

Using motorbikes, pickup trucks, motorized gliders, and speed boats, the militants streamed into Israeli urban areas including Ashkelon, Sderot, and Ofakim, which is about 22 kilometers (13 miles) from Gaza.

The gunmen attacked a rave party attended by hundreds of young Israelis near Kibbutz Reim, close to Gaza, Israeli media reported.

Israel said Hamas has taken more than 100 hostages in Israel. They include an unknown number of Americans and Germans.

The militants overran several locations inside Israel, including a Sderot police station where they engaged in a shootout with Israeli forces on Sunday.

How Israel is responding

Prime Minister Benjamin Netanyahu has vowed to reduce to "rubble" Hamas hideouts in Gaza, an impoverished enclave of 2.3 million people hemmed in by an Israeli blockade for more than 15 years.

The army said it has deployed tens of thousands of soldiers to fight the militants who were still "on the ground" Sunday on Israel territory.

It has also carried out air strikes on Hamas positions inside Gaza, in an operation it has dubbed "Swords of Iron".

Army spokesman Richard Hecht said the air raids had struck 800 targets including Gaza tunnels, buildings, and other infrastructure.

The military said it aims to rescue Israeli hostages and then evacuate the entire region within 24 hours.

Almost 1000 killed

Israel says Hamas gunmen have killed more than 600 people and wounded over 2,000 in Israeli cities, towns, and kibbutz communities.

AFP journalists have seen the bullet-riddled bodies of civilians lying on the streets in at least three locations in Israel: the city of Sderot, the nearby kibbutz of Gevim, and Zikim beach north of the Palestinian coastal enclave.

An unknown number of people were reportedly killed at the rave.

On the Gaza side, at least 370 people have been killed and more than 2,200 wounded, taking the combined toll to almost 1,000 dead.

A British man who had been serving in Israel's army was among those killed in the Hamas attack, his family said.

Two Ukrainian women who had been living in Israel were also killed, Ukraine said.

Thailand has said two of its citizens were killed, while Cambodia reported the death of a Cambodian student.

What Hamas said about the offensive

Hamas said it fired 5,000 rockets in an offensive it has branded "Operation Al-Aqsa Flood".

Its chief Ismail Haniyeh on Saturday vowed to press ahead with "the battle to liberate our land and our prisoners languishing in occupation prisons".

Hamas has called on "resistance fighters in the West Bank" as well as in "Arab and Islamic nations" to join the battle.

Early on Sunday, Lebanon's Iran-backed Shiite militant group Hezbollah said it launched missiles and artillery shells into northern Israel "in solidarity" with the Hamas offensive.

The Israeli army said it retaliated with artillery fire.

Elsewhere, media outlets in Egypt said a policeman opened fire on an Israeli tour group in the northern city of Alexandria on Sunday, killing two Israelis and one Egyptian.

How the world has reacted

United Nations Secretary-General Antonio Guterres condemned "in the strongest terms" Hamas' attack on Israel and called for "diplomatic efforts to avoid a wider conflagration".

The West, much of which has designated Hamas a "terrorist" organization, has also condemned the Islamist group's assault on Israel.

President Joe Biden said the United States support for its key ally Israel was "rock solid and unwavering". The White House said on Sunday he had ordered "additional support" for Israel.

The European Union chief Ursula von der Leyen said: "I unequivocally condemn the attack carried out by Hamas terrorists against Israel."

Iran's President Ebrahim Raisi said the Islamic Republic supported the Palestinians' right to self-defense and warned Israel must be held accountable for "endangering the security of nations in the region".

Russia has called for an "immediate ceasefire".

Turkish President Recep Tayyip Erdogan, who strongly supports the Palestinian cause, on Sunday urged both sides "to support peace".

Saudi Arabia appealed for an "immediate halt to the escalation between the two sides, protection of civilians, and self-control".