On Saturday, Israel attacked Beit Lahiya, targeting residential buildings. At least 87 people were killed or missing, according to the government press service.

Israel laid siege to northern Gaza more than two weeks ago and has since violently attacked anyone remaining in the area, resulting in the deaths of many civilians.

Here’s what you need to know about the ongoing Israeli attack on northern Gaza:

What is Israel doing to northern Gaza?

Israel launched an offensive in northern Gaza on October 6, saying it was aimed at preventing Hamas from regrouping.

Israeli army spokesman in Arabic Avichai Adraei said Hamas had created “a terrorist infrastructure in your region, using the population, shelters and medical facilities as human shields.”

Israel demanded the evacuation of civilians from large areas including Jabaliya, Beit Lahiya and Beit Hanoun, urging residents to flee south, including to the already overcrowded “humanitarian zone” at al-Mawasi.

Israel has attacked humanitarian zones several times, prompting the United Nations to repeatedly say that no place in the enclave is safe.

“We feel like bodies without a soul. The shelling of our house was intense and merciless, despite the presence of children and women inside,” one resident of the northern Gaza Strip told Al Jazeera. “Bodies remain on the streets. They became food for dogs.”

Rescue efforts in the north have been hampered by communications blackouts and roadblocks due to the siege.

Meanwhile, the Israeli army released footage showing dozens of Palestinians being rounded up near an Indonesian hospital where many had taken refuge – with people in wheelchairs visible among those detained.

How many people are still there?

The UN estimates that the evacuation order affected about 400,000 people living there, roughly 20 percent of Gaza’s population.

Many of them are trapped and unable to escape due to intense bombing by Israeli snipers and ground troops.

UN human rights chief Volker Türk warned Israel on Thursday that “any forced displacement of a large part of the population of northern Gaza would amount to a war crime.”

Analysts say Israel’s evacuation orders from the Gaza Strip indicate that those unable or unwilling to leave Gaza are being considered military targets, with “evacuation zones” being treated as “kill zones.”

What are the living conditions of people in northern Gaza?

No food aid has reached the north since October 2, the UN acting under-secretary-general for humanitarian affairs and relief said in a report on Wednesday, adding that “all essential supplies for survival are running out.”

She warned that while distribution of “existing food supplies” was ongoing, those supplies were “dwindling rapidly.”

The UN World Food Program said on October 12 that the north was “effectively cut off and we cannot work there.”

James Smith, an emergency doctor who recently returned from working in the Gaza Strip, told Al Jazeera that he joined several aid and medical convoys trying to move from the south of Gaza to the north.

“More often than not, we were denied access by the Israeli military stationed at the checkpoints,” he said. “Very few UN convoys that tried to reach the north reached this place. Sometimes it also meant we couldn’t pick up wounded and sick patients from the north.”

The Israeli military has denied restricting humanitarian aid supplies, saying that since October 1, more than 9,000 tons of aid have entered Gaza through various checkpoints.

The statement said some of this aid was transferred directly to the northern Gaza Strip.

The government press office denied the claim, saying Israel’s “lies” about allowing the trucks to enter were completely false.

How many people did the Israeli army kill?

Israel has killed at least 450 people in northern Gaza since its siege on October 6, according to medics who spoke to Al Jazeera.

The main target of Israeli attacks in the north was Jabaliya, the largest refugee camp in the Gaza Strip. At least 33 people were killed in Jabaliya on Friday.

Can victims get medical care?

In northern Gaza, three hospitals continue to partially operate – al-Auda, Indonesian and Kamal Adwan Hospital.

During Israel’s two-week siege, these medical facilities saw a massive influx of patients, according to Gaza’s health ministry.

On Friday, the director general of the ministry’s hospitals, Muhammad Zakout, said all three facilities were bombed during the latest Israeli operation.

The ministry said two patients at an Indonesian hospital died due to a power outage and an Israeli blockade that prevented medical supplies from reaching them.

Meanwhile, one person was killed and others were injured after Israeli forces blew up the entrance to Kamal Adwan Hospital on Saturday.

However, despite an evacuation order from the Israeli military, doctors at all three institutions refused to leave their patients.