A group of 38 aid agencies on Monday urged the international community to take action to secure a ceasefire in Gaza to prevent "another widespread humanitarian disaster."
The groups also called on the international community to pressure Israel to keep crossings into Gaza open to allow "essential humanitarian aid" into the territory as hostilities with Israel continue.
"World leaders cannot sit by while civilian casualties in Gaza and Israel continue to mount," said Oxfam country director Nishant Pandey.
"We urgently need to enforce a ceasefire," Pandey said in the statement, saying the ongoing conflict would only make life worse for civilians already suffering the impact of five years of an Israeli blockade and a devastating 22-day Israeli war between December 2008 and January 2009.
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The conflict "will only deepen despair, create more insecurity, and jeopardise chances for Israelis and Palestinians to reach a just and durable peace," he said.
The groups said medicines were running short in Gaza hospitals and the situation would only worsen as the fighting continued.
"If global leaders do not intervene, Gaza stands on the brink of yet another humanitarian crisis," said Aleksandar Milutinovic, country director for Mercy Corps.
By early Monday evening, 99 Palestinians and three Israelis had been killed in six days of conflict that began with Israel's targeting of a senior Hamas official.
Since then, Israel has carried out hundreds of air strikes across Gaza, and militants have launched hundreds of rockets into the Jewish state.