Gaza 'soon without fuel, medicine and food'

The Gaza Strip could be on the brink of a new humanitarian crisis if supplies are not allowed in, authorities say, as Israel responds to the Hamas attacks.

Residents say aid has not reached the enclave since Saturday, and on Monday Israel declared a "complete siege" on the territory - saying electricity, food, fuel and water would be cut off.

Gaza is home to about 2.3 million people, 80% of whom rely on aid.

More than 500 people have died there in Israel's retaliatory strikes.

Israel controls the airspace over Gaza and its shoreline, and restricts who and what goods can cross its borders.

Egypt also strictly controls what or who can pass through its own border with Gaza.

Since the attacks began on Saturday morning, Israel has stopped all supplies entering Gaza, including food and medicine.

Many are currently without electricity and internet, and could soon be out of essential food and water supplies.

Authorities have warned that fuel will run out within 24 to 72 hours. The UN's humanitarian agency, OCHA, has also warned of fuel supplies lasting a matter of days.

Even before the latest restrictions, residents of Gaza already faced widespread food insecurity, restrictions on movement and water shortages.

On Monday, Israel's Defence Minister Yoav Gallant said it would impose a "complete siege" on the territory.

"No electricity, no food, no water, no gas - it's all closed," he said, adding that "we are fighting animals and are acting accordingly."

The Israeli infrastructure minister later ordered the immediate cut-off of water supplies to Gaza, saying: "What was in the past will no longer be in the future."

In a statement released before those announcements, the Palestinian health ministry said hospitals were facing a shortage of medicines, medical supplies and fuel due to Israel's actions.

It called on international actors to urge Israel to "restart power lines" and to supply emergency needs in the form of medicine, fuel and power generators.

Israel has launched massive retaliatory air strikes into Gaza since Saturday, killing at least 511 people and injuring 2,750, according to the Palestinian health ministry.

Sunday night saw a particularly heavy barrage of strikes, potentially the biggest Gaza has experienced in years - throughout the night several loud bangs could be heard in quick succession across the Gaza Strip.

As the strikes continued after dawn, black smoke filled the sky, and the dust from collapsed buildings could be tasted in the air.

Some of the strikes targeted the border area in the east of Gaza, from where Hamas launched their attacks on Saturday morning. Israel appears to be targeting those areas to try and shore up security there.

There have also been reports from witnesses of Israel using artillery fire in the border area.

Israel said it is striking Hamas targets in Gaza, but there are reports of civilians being hit.

The Palestinian Ministry of Foreign affairs said two refugee camps in Gaza - Al-Shati (also known as the Beach camp) and Jabalia camps - were hit by Israeli airstrikes, reportedly leaving several injured and dead.

Video shared online from Jabalia showed widespread chaos, including a body being carried away and a man covered in blood and dust.

The foreign ministry also said air strikes hit a United Nations school in Gaza that was housing hundreds of civilians, including children and the elderly.

The UN confirmed the attack, saying the school was "severely damaged", but that no one was killed.

There have also been reports of a mosque, as well as homes, being hit.

According to Associated Press, 19 members of the same family were killed in a strike in Rafah, in the south of Gaza.

The UN said on Monday 123,538 people in Gaza have been internally displaced, mostly "due to fear, protection concerns and the destruction of their homes".

The Office for the Coordination of Humanitarian Affairs (OCHA) added that 73,000 people are sheltering in schools.