An Israeli attack on two schools in Gaza City left at least 15 people killed and dozens injured in the Tuffah district of the besieged enclave.
The schools targeted, Abdel Fattah Hamoud and al-Zahraa, were destroyed with many Palestinians still missing and trapped under the rubble, according to local civil defence teams who were still working to pull people out.
Displaced Palestinians were sheltering in the schools, which were reportedly targeted without any prior warning.
Earlier on Thursday, Israeli forces stepped up airstrikes across the Gaza Strip, killing at least five Palestinians in a house in the heart of Gaza City.
Another airstrike in the southern city of Khan Younis killed one person and wounded others, according to medics.