Three partially functioning hospitals treating severely wounded patients and sheltering thousands of displaced Palestinian civilians in northern Gaza are now out of service after coming under intense Israeli fire, a Gaza health official told Al Jazeera, as the siege on Jabalia enters its third week, with at least 33 more people killed in the northern area.

Israeli forces bombed al-Awda Hospital in Jabalia early on Saturday, and have also shelled Kamal Adwan and the Indonesian hospitals in Beit Lahiya over the past few hours, Al Jazeera correspondents have reported.

“We cannot count the number of those killed. The numbers are terrifying,” the official told Al Jazeera.

At least one person has been killed and several others were wounded in the strike at the entrance of the laboratory of Kamal Adwan Hospital, Gaza’s Health Ministry said.

The Palestinian news agency Wafa also reported that because of the military siege, two intensive care unit patients at the Indonesian Hospital have died on Saturday.

In another Israeli attack on central Gaza’s Maghazi refugee camp, at least 16 people were killed, the Palestinian official news agency WAFA said on Saturday, adding that there are still missing people under the rubble.

At least seven people were also reported killed in a separate Israeli strike on a school sheltering Palestinian refugees in al-Shati camp, just west of Jabalia. In Jabalia itself, an air strike on Saturday afternoon killed five more people.

Another four people were reported killed in another Israeli strike in al-Nuseirat refugee camp, according to our Al Jazeera team from Gaza.

In Rafah city, southern Gaza Strip, two people were killed in an Israeli drone airstrike on the Khirbet area.

In all, the death toll has surpassed the 67 killed in Israeli attacks across Gaza in the last 24 hours, as earlier reported by health authorities in the enclave. At least 450 have been killed since the siege began two weeks ago.

Al Jazeera’s Tarek Abu Azzoum, reporting from Deir el-Balah in central Gaza, said witnesses in northern Gaza told him the second and third floors of the Indonesian Hospital, as well as its courtyard, have been hit, resulting in “a number of casualties”.

At least 40 patients are trapped inside the hospital and Israeli tanks have surrounded it, he said.

Meanwhile, the attack on al-Awda Hospital cut power to the medical facility. Witnesses also told Abu Azzoum the situation in other parts of Jabalia had “severely deteriorated” since Friday.

“They said that they are surrounded by Israeli tanks and that destruction is everywhere. They said that the smell of death is in every corner of the Jabalia refugee camp,” he added.

“We have to remember that Jabalia is already under a crippling siege with no food and water entering the area for the 15th day now,” Abu Azzoum said.

Communications and internet services had also been completely been cut off, disrupting rescue operations, he said, adding that Israeli forces have been advancing further into the centre of Jabalia and fighting with Hamas forces.

Meanwhile, Palestinian authorities warned the death toll from the latest strikes on Jabalia could rise, as some people were believed to be still trapped under the rubble.

The Palestinian official news agency, Wafa, said children were among the 33 confirmed dead. At least 85 others were wounded, some critically, raising fears of more fatalities.

The Israeli military said its operation in Jabalia is intended to stop Hamas fighters regrouping for more attacks. But the Health Ministry in Gaza said most of the people killed were civilians.

On Friday, health officials appealed for fuel, medical supplies and food to be sent immediately to the three northern Gaza hospitals which have been overwhelmed by the number of patients and injuries.

The World Health Organization (WHO) has also accused Israel of preventing at least 50 medical specialists belonging to eight groups from entering Gaza, the first such case of entire organisations being blocked from participating in humanitarian efforts in the besieged territory.

Northern Gaza, once home to more than half of the territory’s 2.3 million people, was bombed to rubble in the first phase of Israel’s assault a year ago. More than 42,000 Palestinians have been killed in Israel’s genocide on Gaza so far, according to Gaza’s health authorities.