Israel launched strikes on Gaza on Sunday after it expanded an evacuation order for Rafah.
Gaza's civil defence agency said two doctors were among those killed on Sunday in the central town of Deir al-Balah as AFP correspondents reported heavy gunfire from Israeli helicopters near Gaza City.
UN Secretary-General Antonio Guterres urged an immediate halt to the war on Gaza, the return of hostages and a "surge" in humanitarian aid to the besieged Palestinian territory.
"I repeat my call, the world's call for an immediate humanitarian ceasefire, the unconditional release of all hostages and an immediate surge in humanitarian aid. But a ceasefire will only be the start," Guterres said in a video address to an international donors' conference in Kuwait.
