An employee inspects the damage to the al-Aqsa hospital, shelled on July 21 (Mohammed Abed/ AFP).
A Palestinian health official said that 12 shells had been fired at the al-Aqsa hospital in the town of Deir al-Balah, striking parts of the building that included the intensive care unit and the surgery department.
The wounded were shown in live footage from Hamas's local TV station in al-Aqsa being moved on gurneys to the emergency department.
The health official, Ashraf al-Kidra, told the Associated Press that 30 of those hurt were working as medical staff at the hospital.
The Israeli military said it was looking into the report, which came from a different part of Gaza to the al-Wafa hospital that was damaged by missile fire last week.
A doctor at the hospital, Fayez Zidane, told the al-Aqsa station that shells hit the third and fourth floor as well as the reception area.
"There is still shelling against the hospital," he said. He said he found bits of a rocket, presumably from one of the projectiles.
Zidane appealed to the Red Cross and a nearby hospital to send help.
But despite speaking to the US President in a phone call on Sunday night, Benjamin Netanyahu, the Israeli Prime Minister, said Israel's offensive would continue "as long as necessary" to end rocket attacks from Gaza.