Rescuers say they've found more than 250 bodies at the site of an Israeli music festival attacked by Hamas militants in an unprecedented assault on Saturday
The Israeli military says at least 700 people have died in the attacks overall, more than 2,000 were injured, and that a number of hostages are being held in Gaza
Retaliatory Israeli air strikes have killed at least 413 people in the Gaza Strip, with 2,300 wounded, according to the latest update from Palestinian officials
The US has announced more support for Israel by sending munitions and boosting forces in the region
The family of a British man serving in the Israeli military, Nathanel Young, say he was killed in an attack; several other nations have said their own citizens have died or been abducted
The wave of attacks launched by the Hamas militant group on Saturday morning was the biggest escalation between the two sides for decades
You can watch live BBC News coverage by clicking the 'play' button at the top of this page
Rushdi Abu Alouf
BBC News, Gaza
Hamas says they have fired 150 rockets in response to the Israeli air strike on the Palestine Tower, an 11-story building in the centre of Gaza City.
The sound of explosions can be heard across Gaza.
The death toll is now reported to be at least 150 in Israel now, with at least 1,000 injured, according to local media citing Israeli officials.
Israel's energy and infrastructure minister Israel Katz said that Israel will cut off its electricity supply to Gaza Strip.
"I have signed an order instructing Israel's electric company to stop the electricity supply to Gaza," Katz said in a statement.
Power cuts are an everyday occurrence in Gaza.
Gaza's power authority says 80% of Gaza electricity supplies have been shut following Israel's announcement.
Before Katz's statement, Gaza residents were already reporting more frequent power cuts since the Israeli strikes started this morning.
The Strip gets most of its power from Israel together with further contributions from Gaza's only power plant and a small amount from Egypt. Both the power plant and many people's individual generators depend on diesel fuel, and supplies brought in via Israel.
Jeremy Bowen
International Editor
Image source, Getty ImagesIsrael launched a wave of air strikes on Gaza after Palestinian assault on its territory
Israel was taken by surprise by the most ambitious operation Hamas has ever launched from Gaza.
The scale of what's been happening is unprecedented. Hamas breached the wire that separates Gaza from Israel in multiple places in the most serious cross-border attack Israel has faced in more than a generation.
Videos and photos of dead Israelis, civilians as well as soldiers, are all over social media.
For months, it has been clear that there was a deepening risk of an explosion between Palestinian armed groups and Israel.
But no one expected Hamas to conceive and meticulously plan such a complex and coordinated operation out of Gaza.
Here's a summary of the latest developments:
The Israeli army spokesperson earlier confirmed that "soldiers and civilians" have been abducted by Palestinian militants, and that there were hostage situations in the city of Ofakim and kibbutz Be'eri, where special forces were involved.
Now, Hamas has said that "the Israeli captives have been placed in secured places and in tunnels".
They haven't given any details on where these "secure places" or tunnels are, and whether they are back in Gaza or in Israel.
As part of Israel's retaliatory strikes, its warplanes have hit several buildings in the centre of Gaza City, including an 11-storey building called Palestine Tower.
It houses Hamas radio stations on the rooftop and also boasts a cinema.
The video below shows the moment the building was struck - it collapses soon after.
Gaza: Israel fighter jets destroy high-rise buildings
Israel's health ministry has given updated numbers to Israeli media of the victims of Hamas's attack since early on Saturday.
The death toll is now reported to be about 100 and the number of people taken to hospital at 985.
Public broadcaster Kan says dozens of those being treated are in a critical condition.
The casualty numbers are expected to rise still further.
Barbara Plett Usher
North America correspondent, BBC News
The US response to the unprecedented Hamas offensive has been swift and unsurprising.
Top officials, from President Biden to the secretaries of state and defense, have unequivocally condemned it, and declared their unwavering commitment to Israel’s right to defend itself.
The Pentagon added that it will work to ensure Israel has what it needs to do so.
The Biden administration has had a strained relationship with Israel’s right-wing government. It has warned about threats to Israeli democracy because of a plan to overhaul the judiciary - and criticised a particularly aggressive settler policy in the West Bank.
Tensions had begun to ease in the past month, and now US support for Israel’s response to the Hamas attacks will become the focus.
Former President Donald Trump also backed Israel’s right to defend itself with overwhelming force. And he took the opportunity to blame the Biden administration for policies he said undermined his own efforts to bring "so much peace to the Middle East" by brokering normalisation agreements between Israel and Arab countries.
In fact, the Biden administration has been negotiating a similar agreement between Saudi Arabia and Israel. Any deal would have required some concessions to the Palestinians.
The future of that initiative now depends on how the new Hamas-Israel conflict plays out.
Ece Göksedef
Live reporter
Hassan Jber, a 60-year-old journalist who lives in Gaza with his family, says that residents of the city woke up to the sounds of bombing and shooting this morning, before learning that Palestinian gunmen had attacked Israeli villages.
He said Hamas had been under pressure from people in Gaza to mount an attack against Israel over "settler attacks on Palestinians".
"They broke the silence today," he said.
He says that he doesn’t support any kind of violence but he knows that neither Hamas nor Israel “will stop their attacks”.
We have just seen the statement by US President Joe Biden on his phone call with Israeli PM Benjamin Netanyahu:
"The United States unequivocally condemns this appalling assault against Israel by Hamas terrorists from Gaza," the statement says.
Quote MessageTerrorism is never justified. Israel has a right to defend itself and its people. The United States warns against any other party hostile to Israel seeking advantage in this situation. My Administration’s support for Israel’s security is rock solid and unwavering."
Joe Biden
The statement adds that Biden and his team are tracking the situation closely, and that he will remain in close touch with Netanyahu.
"Our goals are that all the terrorists will be killed, that all the communities will be rid of terrorists," the IDF statement continues.
It also warned people living in Israel near the Gaza Strip to stay sheltering inside until then.
The statement continues that the IDF is carrying out air strikes in Gaza and will later continue with "heavy ground means"
In its statement, the Israeli army also confirms that there are hostage situations in the city of Ofakim and kibbutz Be'eri. It says special forces are involved and "live firefights" are ongoing.
Separately, the army confirms Israeli soldiers have been killed, but does not provide numbers.
More from the Israel Defense Forces, who have confirmed their troops are fighting in 22 locations in a statement.
"There is no community in southern Israel where we do not have forces," it says.
A spokesperson for the Israeli Defense Forces has confirmed that "soldiers and civilians" have been abducted by militants. The military is not confirming numbers.
This video shows people moving through the rubble of a building in Gaza, after it was destroyed by an Israeli air strike.
Emergency services say the death toll in Israel from a surprise attack by Palestinian militant group Hamas has increased to 70.
The Magen David Adom emergency medical service says “we can update the toll to 70 killed, and hundreds wounded seriously, moderately and lightly".
Frank Gardner
Security correspondent
Israeli officials deny reports that an Israeli Defense Forces (IDF) major general has been kidnapped.
Hamas claims it has taken 53 "prisoners of war" - ie. hostages.
The IDF is not commenting on more precise details.
Graeme Baker
Live reporter
Palestinian militants attacked several military outposts - footage on social media shows militants inside an unidentified base, with burning Israeli vehicles including a Merkava tank.
Such incursions would give ample opportunity to capture Israeli officers and soldiers.
Palestinian groups have in the past used hostages as bargaining chips to secure the release of militants held by Israel.
Israel secured the release of its soldier Gilad Shalit by freeing more than 1,000, external Palestinian prisoners in 2011. Around 200 had been on life sentences for preparing or carrying out attacks inside Israel.
According to the latest report, external by B’Tselem, the Israeli human rights group, there were 4,499 Palestinians in prison on what Israel defined as “security” grounds in June. That number included 183 from the Gaza Strip. Several hundred more are being held for illegally being inside Israel.
Jo Floto
Middle East bureau chief in Jerusalem
This is a nightmare scenario for many Israelis. We understand that dozens of hostages both military and civilian have been taken by Hamas.
Some are thought to be holed up in some of the small towns near the Gaza Strip. Others we know have been taken back into Gaza.
This is an extraordinary situation.