Palestinians salvage what little of their belongings they could from their homes. File/AP

More than a million people have fled their homes in the Gaza Strip ahead of an expected Israel invasion that seeks to eliminate Hamas’ leadership after its deadly incursion. Aid groups warn an Israeli ground offensive could hasten a humanitarian crisis.

Israeli forces, supported by US warships, positioned themselves along Gaza’s border and drilled for what Israel said would be a broad campaign to dismantle the Palestinian Hamas group. A week of blistering airstrikes have demolished neighbourhoods but failed to stop Hamas rocket fire into Israel.

The war that began Oct. 7 has become the deadliest of five Gaza wars for both sides, with more than 4,000 dead. The Gaza Health Ministry said 2,670 Palestinians have been killed and 9,600 wounded. More than 1,400 Israelis have been killed, and at least 155 others, including children, were captured by Hamas and taken into Gaza, according to Israel.

Following an Israeli order to move to the south of the Gaza Strip, people have fled their homes in the north of the enclave to seek shelter wherever they can, including on the streets and in UN-run schools.

Palestinians carrying whatever belongings they can, in bags and suitcases, or packed onto three-wheeled motorbikes, battered cars, vans and even donkey carts have become a common sight.

Israel's Iron Dome anti-missile system intercepts rockets launched from the Gaza in Israel, on Sunday night. Reuters

"No electricity, no water, no internet. I feel like I'm losing my humanity," said Mona Abdel Hamid, 55, who fled Gaza City to Rafah in the south of the enclave, and is having to stay with strangers.

US President Joe Biden said in an interview with the CBS news programme 60 Minutes that while invading and "taking out the extremists" was needed, any move by Israel to occupy Gaza would be a "big mistake".

"We are at the beginning of intense or enhanced military operations in Gaza City," spokesman for the Israeli Defense Forces (IDF) Jonathan Conricus said.

"It would be unsafe for civilians to stay there," he added.

Hamas backer Iran and Lebanon's Hezbollah, which is also supported by Tehran, have warned that an invasion of Gaza would be met with a response.

"No one can guarantee the control of the situation and the non-expansion of the conflicts" if Israel sends its soldiers into Gaza, said Iran's Foreign Minister Hossein Amir-Abdollahian.

Fire along the Israeli-Lebanese border has intensified in the last week, prompting Israel to shutter the area to civilians.

A Palestinian civil defence officer is carried into the Shifa hospital after Israeli airstrikes early on Monday. AP

In Gaza, hospitals are becoming overwhelmed with increasing numbers of dead and injured, with officials saying Sunday that some 9,600 people have been wounded.

Israeli energy minister Israel Katz on Sunday said water supplies to southern Gaza had been switched back on.

But power outages threaten to cripple life-support systems, from sea water desalination plants to food refrigeration and hospital incubators.

Even everyday functions -- from going to the toilet, showering and washing clothes -- are almost impossible, locals said.

Agencies