The World Health Organization said it lost communications with its contacts in Al-Shifa Hospital in northern Gaza.
"As horrifying reports of the hospital facing repeated attacks continue to emerge, we assume our contacts joined tens of thousands of displaced people and are fleeing the area," it said.
The WHO added it "has grave concerns for the safety of the health workers, hundreds of sick and injured patients, including babies on life support and displaced people who remain inside the hospital. The number of inpatients is reportedly almost double its capacity."
Israeli jets strike 'terror infrastructure sites in Syria': army
Israeli fighter jets carried out strikes against "terror infrastructure" targets inside Syria in response to cross-border fire directed at the Golan Heights, the military said on Sunday.
"A short while ago, in response to the attack toward the Golan Heights yesterday (Saturday), IDF (Israel Defense Forces) fighter jets struck terror infrastructure sites in Syria," the army said on Telegram.
On Saturday, the army said that two projectiles fired from Syria had landed in uninhabited parts of the Golan Heights and that rocket alert sirens had sounded in the region.
Israel also struck targets in Syria on Friday after a drone launched from there crashed into a school in the southern town of Eilat.
Israel occupied much of the Golan Heights in the 1967 Six Day War, and later annexed it in a move that was never recognised by the United Nations.
Exchanges of cross-border fire have also taken place regularly along the frontier with Lebanon, as Israel continues to press its offensive against Hamas.