The United Nations Secretary-General and the United States have condemned an attack on a United Nations school in a refugee camp Gaza, which has killed at least 16 people.

Thousands of people were sheltering at the United Nations school in the Jabalya camp, when artillery shells struck the compound. UN Secretary General Ban Ki-Moon said that “all available evidence points to Israeli artillery as the cause”.

“Nothing is more shameful than attacking sleeping children” said the Secretary-General denouncing the attack. “I condemn this attack in the strongest possible terms. It is outrageous. It is unjustifiable. And it demands accountability and justice.”

See more of his statement here.

The Secretary-General's remarks came as the United States White House also condemned the shelling, with National Security Council spokesperson Bernadette Meehan saying,

“We are extremely concerned that thousands of internally displaced Palestinians who have been called on by the Israeli military to evacuate their homes are not safe in UN designated shelters in Gaza.”

However, the United States did not accuse Israel of having responsibility for the shelling and added there were conflicting reports about the incident.

Meanwhile, the commissioner-general of the UN agency for Palestinian refugees (UNRWA) Pierre Krähenbühl also condemned the shelling as a "serious violation of international law by Israeli forces".

Krähenbühl went on to add,

"Last night, children were killed as they slept next to their parents on the floor of a classroom in a UN-designated shelter in Gaza. Children killed in their sleep; this is an affront to all of us, a source of universal shame.”

“Today the world stands disgraced."