Gaza is “becoming a graveyard for children,” the United Nations chief warned on Monday as the death toll rises and calls grow around the world for a ceasefire, one month into Israel’s assault on Hamas - the militant group that runs the enclave.

“The nightmare in Gaza is more than a humanitarian crisis. It is a crisis of humanity,” UN Secretary-General António Guterres told reporters in New York, adding that the need for a ceasefire is becoming “more urgent with every passing hour.”

“The parties to the conflict – and, indeed, the international community – face an immediate and fundamental responsibility: to stop this inhuman collective suffering and dramatically expand humanitarian aid to Gaza,” he said.

From the start, global aid organizations and rights groups have warned that such an assault would be catastrophic for Gaza, which has been cut off from much of the world for nearly 17 years. A blockade imposed by Israel and Egypt meant severe restrictions on the movement of goods and people – contributing to widespread poverty, hunger and dependency on international aid.

The devastation of Israel’s attacks on Gaza is now becoming apparent, with the Hamas-controlled health ministry in the enclave saying Monday that more than 10,000 people have been killed since the war began. That includes more than 4,100 children and 2,600 women, the ministry said.

It’s unclear how many combatants are included in the total, which CNN cannot independently confirm.