Jerusalem, May 20 -- At least 50 people have been killed in Israeli strikes on the Gaza Strip since midnight on Tuesday, Al Jazeera reported, citing Palestinian medical sources.

Israel has been bombarding Gaza City, northern and central Gaza. At least 12 people died in an attack on the Musa bin Nusair School sheltering refugees in Gaza City. Another 13 were killed in strikes on residential buildings in the city of Deir al-Balah, while an attack on the Nuseirat refugee camp killed 15.

Overall, over 3,300 people have been killed and more than 9,300 people have been injured in the Gaza Strip since Israel resumed shelling of the Palestinian enclave on March 18, the Gazan health authority said.

Gaza's civil defense forces warned on Sunday tha...