Israeli air strikes in the heart of Gaza City on Sunday killed at least 23 people and wounded 50, Gaza Health Ministry said.
It was the deadliest single attack since the start of heavy fighting between Israel and Gaza’s militant Hamas rulers nearly a week ago.
Rescuers were racing to pull survivors and bodies from the rubble.
Earlier, Israel said it bombed the home of Gaza’s top Hamas leader in a separate strike, the third such strike targeting the homes of Hamas leaders.
In the aftermath, sirens warning of rocket attacks sounded in Israeli border towns shortly after dawn as hostilities stretched into a seventh day with no sign of abating.
At least 153 people have been killed in Gaza since Monday, including 42 children, health officials said.
Israel has reported 10 dead, including two children.
The United Nations Security Council was due to meet later on Sunday to discuss the worst outbreak of Israeli-Palestinian violence in years.
U.N. Secretary-General Antonio Guterres reminded all sides “that any indiscriminate targeting of civilian and media structures violates international law and must be avoided at all costs,” U.N. spokesman Stephane Dujarric said in a statement on Saturday.
Both Israel and Hamas, the Islamist group that runs the enclave, insisted they would continue their cross-border fire after Israel destroyed a 12-storey building in Gaza City that housed the U.S. Associated Press and Qatar-based Al Jazeera media operations.
The Israel military said the al-Jala building was a legitimate military target, containing Hamas military offices, and that it had given advance warnings to civilians to get out of the building.
The AP condemned the attack, and asked Israel to put forward evidence.
“We have had no indication Hamas was in the building or active in the building,” it said in a statement.
In what Hamas called a reprisal for Israel’s destruction of the al-Jala building, Hamas fired 120 rockets overnight, the Israeli military said, with many intercepted and around a dozen falling short and landing in Gaza.