More Palestinians have succumbed to their burn wounds after an Israeli strike hit their shelter in Gaza City overnight, raising the death toll there to at least 13, with reports of six people remaining under the rubble.

The school-turned-shelter was one of several sites hit in Gaza on Wednesday. Gaza’s civil defence said four more bodies were pulled from two nearby homes.

Rescue teams know at least six more victims remain trapped beneath the rubble in Gaza City, but they are unable to reach them, reported Al Jazeera’s Hani Mahmoud from the city.

“It’s not just their inability to get to the area,” he said. “They lack the heavy equipment needed to remove the rubble and recover the bodies.”

In total, 39 people were killed and 105 injured across the territory in the past 24 hours, the Health Ministry reported.

The latest attacks came as Palestinian Authority President Mahmoud Abbas urged Hamas to release the remaining Israeli captives in Gaza.

Hamas, which governs Gaza and rivals Abbas’s PA, has said it would release all captives in exchange for a full Israeli withdrawal and a permanent end to the war – but has rejected Israel’s demand to disarm, calling it a “red line”.

Despite a monthlong deadlock in ceasefire negotiations following Israel’s resumption of attacks on March 18, Qatar’s Prime Minister Sheikh Mohammed bin Abdulrahman bin Jassim Al Thani says Doha remains engaged in talks to end the war.

A Hamas delegation arrived in Cairo on Tuesday to discuss a new truce proposal.

Meanwhile, Israel is continuing to block aid, including food and medicine, from entering Gaza for an eighth straight week.

In unusually strong criticism, France, Germany and the United Kingdom called Israel’s blockade “intolerable”.

“Humanitarian aid must never be used as a political tool and Palestinian territory must not be reduced nor subjected to any demographic change. Israel is bound under international law to allow the unhindered passage of humanitarian aid,” a joint European statement said.

Since the war resumed, at least 1,928 Palestinians have been killed, pushing the total death toll above 51,300, according to Gaza’s Health Ministry.