The World Health Organisation (WHO) said it participated in a joint United Nations mission to deliver health supplies and assess the situation at the Al Shifa Hospital in Gaza.
The team delivered medicines and surgical supplies, orthopedic surgery equipment, and anesthesia materials and drugs to the hospital which was "currently minimally functional," the WHO said.
It comes after a WHO-led humanitarian assessment team visited Al Shifa Hospital and saw signs of shelling and gunfire in what was described as a "death zone". They found the hospital unable to function due to scarcity of clean water, fuel, medicine and other essentials.
"Signs of shelling and gunfire were evident. The team saw a mass grave at the entrance of the hospital and were told more than 80 people were buried there," the WHO statement said.
There were 25 health workers and 291 patients, including 32 babies in critical condition, remaining in Al Shifa.
The team, which included public health experts, logistics officers and security staff from various UN departments, was able to spend only an hour inside the hospital on Saturday due to security concerns, WHO said, adding it was coordinated with the Israeli military to reduce risks.
"Over the next 24–72 hours, pending guarantees of safe passage by parties to the conflict, additional missions are being arranged to urgently transport patients" to other hospitals in the south of Gaza.
The authority added that 2,500 internally displaced people who had sought refuge on Al Shifa grounds were gone after the Israeli Defense Forces issued evacuation orders on Saturday.
WHO also repeated its call for an immediate ceasefire and sustained humanitarian assistance, saying options for medical care in Gaza were dwindling.