Hospitals are running out of supplies and emergency responders are often unable to reach people trapped under debris.
"The number of dead is high, and people are under the rubble, missing," Muhammad Abu Halima, a 40-year-old Jabalia resident, told AFP.
"For over a week there has been no hope, no water and no means of life," he said.
Israel's army intensified operations in Jabalia last weekend to target Hamas fighters it said were regrouping there.
It later announced it had effectively laid siege to the area in northern Gaza, and issued evacuation orders for residents.
The military's latest offensive in northern Gaza has caused more suffering for hundreds of thousands of trapped people, according to the UN agency for Palestinian refugees, UNRWA.
Vast areas of Gaza have been devastated by Israel's retaliatory assault on the territory after the October 7 Hamas attack on Israel last year that sparked the war.
Since the Jabalia operation began, residents, health care officials and emergency responders said intense shelling and closed roads have prevented aid deliveries, choking off vital supplies to medical facilities.
"We are under Israeli siege," Hussam Abu Safiya, director of Kamal Adwan Hospital in Jabalia, told AFP.
The hospital has just days' worth of fuel needed to power the facility and medical staff are "exhausted with very few doctors available", he said.
"We are suffering from a blockade on food, medicine, medical supplies and even fuel coming from the south to the north."
On Saturday, family members wept as they mourned and consoled each other at a hospital where loved ones killed in the fighting in Jabalia were wrapped in white burial shrouds.
'Dozens of missing people'
Emergency responders said rescuers' movements had also been increasingly hampered by fighting that prevented them from reaching buildings hit by strikes where people were buried under the wreckage.
"There are dozens of missing people under the rubble, and we cannot reach them at all," said Gaza civil defence agency spokesman Mahmud Bassal.
Bassal said a large number of people had been killed since the Israeli military operation against Jabalia began on October 6.
Despite international outcry over the civilian toll, Israeli Prime Minister Benjamin Netanyahu on Sunday defended the onslaught, saying troops were targeting militants.
"Our brave soldiers are now in the heart of Jabalia, where they are dismantling the Hamas strongholds," he said in a video statement issued by his office.
Hamas on Sunday denounced Israel's operations as a "criminal military campaign".
Netanyahu has repeatedly pledged to achieve total victory in Gaza by eradicating Hamas.
After more than a year of war, the Palestinian militant group is believed to have been dramatically weakened by the killing of several of its leaders and thousands of fighters.
But Hamas has not been crushed outright, and fighters regrouping in pockets of the territory spark renewed offensives by the Israeli military.
For Jabalia resident Hashim Abu Youssef Asaliya, the latest fighting has brought only more suffering.
"Our life is in despair in Jabalia," the 70-year-old told AFP.
"Since the war started, we have been displaced 12 times. This is our life."
