Israeli troops battled Palestinian militants in an urban refugee camp and outside the gates of a nearby hospital on Tuesday as the army expanded operations across northern Gaza, where residents have been without electricity, water or access to humanitarian aid for weeks.

The front line of the war, now in its seventh week, has shifted to the Jabaliya camp, a dense warren of concrete buildings near Gaza City that houses refugees from the 1948 war surrounding Israel’s creation and their descendants.

Israel has been bombarding the area for weeks, and the military said Hamas fighters have regrouped there and in other eastern districts after being pushed out of much of Gaza City.

Fighting has also intensified outside the Indonesian Hospital on the outskirts of Jabaliya, where a strike killed 12 people on Monday. Health officials said on Tuesday that hundreds of patients and displaced people are trapped inside with dwindling supplies after some 200 were evacuated the day before.

The war sparked by Hamas’ October 7 attack on Israel has exacted a heavy toll on Palestinian civilians, particularly those who remain in the north after Israel called on people to flee south.

It’s unclear how many people remain in the north, but the UN agency for Palestinian refugees estimates that some 160,000 people are still in its shelters there, even though it is no longer able to provide services.

Hundreds of thousands of displaced people have packed into UN-run schools and other facilities across southern Gaza. As the shelters have overflowed, people have been forced to sleep on the streets outside, with little shelter from winter rains that have hit the region in recent days.

Across Gaza, there are shortages of food, water and fuel for generators to power basic infrastructure. There has been a territory-wide blackout since Israel cut off fuel imports at the start of the war. Israel continues to strike what it says are militant targets across Gaza, including in the southern evacuation zone, often killing women and children, and officials have said it may soon expand its operations in the south.

Tens of thousands of Palestinians in the north had sheltered in hospitals, but those have steadily been emptied out as the fighting has reached their gates, and most are no longer operational.

Marwan Abdallah, a medical worker at the Indonesian Hospital near Jabaliya, said heavy fighting prevented ambulances from bringing wounded people in.

Munir al-Boursh, a senior health ministry official who said he was inside the hospital, told Al-Jazeera television by phone that Israeli forces had besieged it.