The situation in Gaza City is nothing short of cataclysmic, a UN official has told the BBC, as Israeli tanks and troops continue to advance on the third day of a ground offensive.
Olga Cherevko, a spokeswoman for the UN's humanitarian office, said she had seen a constant stream of Palestinians heading south during a recent visit to the city, but that hundreds of thousands remained.
The World Health Organization (WHO) warned that overwhelmed hospitals were on the brink of collapse because it was being prevented from delivering lifesaving supplies.
The Israeli military said its forces were dismantling terror infrastructure and eliminating terrorists in Gaza City.
It has said its objectives are to free the hostages still held by Hamas and defeat up to 3,000 fighters in what it has described as the group's main stronghold.
However, the offensive on Gaza's biggest urban area, where one million people were living and a famine was confirmed last month, has drawn widespread international condemnation.
The UN and its humanitarian partners have recorded at least 200,000 people crossing from northern to southern Gaza since mid-August, when Israel announced its intention to conquer Gaza City. Around 55,000 have made the journey since Sunday.
Cherevko, who works for the UN humanitarian office in the central city of Deir al-Balah, told the BBC she travelled to Gaza City two days ago - a 29km (18 mile) round-trip that took 14 hours.
The things there, and the scenes on the way to Gaza City, are nothing short of cataclysmic, she recalled.
A constant stream of people [are] crossing from the north to the south, many on foot. Inside Gaza City, it's very crowded still because there are hundreds of thousands of civilians still remaining there.
She warned that many people were unable to comply with the Israeli military's order to evacuate, noting the exorbitant expense of moving belongings or the lack of available transportation.
Furthermore, the WHO's chief, Dr. Tedros Adhanom Ghebreyesus, stated that the Israeli offensive was forcing traumatised families into an ever-shrinking area unfit for human dignity and emphasized the urgent need for medical supplies as hospitals struggle to cope with the influx of patients amidst ongoing strikes.
The Israeli military's operation appears aimed at significantly escalating their presence in Gaza, with reports of heavy bombardment and use of remote-controlled explosives adding to the destruction in civilian areas.
