The last major functioning hospital in northern Gaza was forcibly evacuated by the Israeli military on Friday after dozens of people were reportedly killed in Israeli strikes targeting the area.
Medical staff, including the director of the Kamal Adwan Hospital, have also been detained, Gaza health officials said on Saturday.
The hospital director, Dr Hussam Abu Safiya, was among the first to report that about 50 people had been killed in Israeli air strikes targeting the vicinity of the hospital on Friday.
The IDF had said it was carrying out an operation in the area, alleging the hospital was a "Hamas terrorist stronghold".
On Friday, patients at the hospital were forcibly moved to the nearby Indonesian Hospital which doctors warn is damaged and unsuitable due to a lack of power generators and water.
Eid Sabbah, head of the nursing department at Kamal Adwan, told the BBC the military had ordered the evacuation around 07:00 on Friday, giving the hospital about 15 minutes to move patients and staff into the courtyard.
Israeli troops then entered the hospital and removed the remaining patients, he said.
The IDF said it had "facilitated the secure evacuation of civilians, patients and medical personnel" before beginning the operation.
Seriously ill patients were moved to the nearby Indonesian Hospital, itself evacuated earlier in the week, which medics have described as non-functional.
"You can't call it a hospital, it's more of a shelter. It's not equipped for patients," Gaza's deputy minister of health, Dr Abu-Al Rish, told the BBC on Friday.
Dr Sabbah, from Kamal Adwan Hospital, said: "It's dangerous because there are patients in the ICU department in a coma and in need of ventilation machines and moving them will put them in danger."
He had said critically ill patients needed to be moved in specialised vehicles.
The World Health Organization said the raid "has put this last major health facility in north Gaza out of service".
"Initial reports indicate that some key departments were severely burnt and destroyed during the raid," it posted on X on Friday.
Nadav Shoshani, international spokesman for the Israel Defense Forces (IDF), said in a post on Friday evening on X that a "small fire broke out in an empty building inside the hospital that is under control".
This was when IDF troops were not inside the hospital, he said, adding that "after preliminary examination, no connection was found between IDF activity to the fire".
The director of Kamal Adwan hospital had said on Friday that approximately 50 people had been killed, including five medical staff, in a series of Israeli air strikes targeting the vicinity of the hospital.
The statement from Dr Hussam Abu Safiya said a building opposite the hospital was targeted by Israeli warplanes, leading to the death of a paediatrician and a lab technician, as well as their families.
He said a third staff member who worked as a maintenance technician was targeted and killed as he rushed to the scene of the first strike.
Two of the hospital's paramedics were 500m (1,640ft) away from the hospital when they were targeted and killed by another strike, the statement continued, with their bodies remaining in the street with no-one able to reach them.
The Israeli military said on Friday morning that it was "unaware of strikes in the area of Kamal Adwan hospital" and was looking into the reports that staff had been killed.
Kamal Adwan hospital in Beit Lahia has been under a tightening Israeli blockade imposed on parts of northern Gaza since October, when the military said it had launched an offensive to stop Hamas from regrouping there.
The UN has said the area is under a "near-total siege" as the Israeli military heavily restricts access of aid deliveries to an area where an estimated 10,000 to 15,000 people remain.
In recent days, the hospital's administrators have issued desperate pleas appealing to be protected, as they say the facility has become a regular target for Israeli shelling and explosives.
Oxfam said that attempts by aid agencies to deliver supplies to the area since October had been unsuccessful because of "deliberate delays and systematic obstructions" by the Israeli military.
Additional reporting by Shaimaa Khalil