Israel faces criticism for the number of children killed in airstrikes.

[K Shehzad]

The Israeli military came under mounting criticism on Saturday for the growing number of children that have been killed in airstrikes on Gaza.

Images of children’s bodies circulated on social media on Saturday, along with the video of a bereft Gaza father comforting his wailing infant — the sole child to survive an Israeli airstrike.

At least 145 people have died in Gaza since fighting began on Monday, about 40 of them children, according to the United Nations. Ten Israeli civilians, including two children, have died since Hamas fired rockets into Israel.

“It’s not acceptable!” Simon Coveney, the Irish foreign affairs minister, wrote on Twitter on Saturday, vowing to make a case at the United Nations to hold Israel accountable for the death of children. He said Israel had an obligation under international law “to protect children in conflict & r not doing so!”

The current battle is not the first time children have borne the heavy share of the casualties. In the 2014 conflict, more than 500 children were killed, according to the United Nations, roughly a third of Palestinian fatalities.

Among the deaths this week were eight children killed in a single airstrike around 2 a.m. Saturday in the Shati refugee camp.

“I am appalled by the horrific incident in Al-Shati camp which claimed the lives of 8 Palestinian children, in an Israeli airstrike,” Tor Wennesland, the U.N. Middle East envoy, wrote on Twitter.

Speaking of the children killed on both sides, he added: “I mourn their short lives.” Children “continue to be victims of this deadly escalation,” Mr. Wennesland said. “I reiterate that children must not be the target of violence or put in harm’s way. The hostilities must stop now!”

Gaza’s demographics and the nature of life and warfare there make any fighting dangerous for children, aid workers say.

Relatively few women in Gaza are employed, and the fertility rate is high, leaving the median age in the crowded coastal enclave at just 18, compared to 30 in Israel and 31 worldwide. And Israel says that Hamas positions its fighters in or underneath residential areas, deliberately exposing civilians — and children — to harm.