The border crossing between Egypt and the Gaza Strip opened on Saturday to allow humanitarian aid to trickle into the besieged Palestine territory for the first time since Israel sealed it off following a Hamas attack over two weeks ago.

Twenty trucks were allowed in on Saturday, and more trucks crossed into Gaza on Sunday, The Associated Press reported. In addition to 17 aid trucks reported by Egypt state media, seven fuel trucks escorted by United Nations vehicles were seen entering Gaza.

More than 200 trucks carrying 3,000 metric tons of aid have been waiting near the Rafah crossing for days, while Gaza's 2.3 million Palestinian residents — half of whom have fled their homes — are rationing food and drinking dirty water, AP reported.

Hospitals said they are running low on medical supplies and fuel for emergency generators amid a territory-wide power blackout. The UN agency for Palestinian refugees said it could run out of fuel in Gaza very soon.

Saturday's convoy carried 44,000 bottles of drinking water, a day's supply for 22,000 people, according to UNICEF.

The World Health Organization said four of the trucks carried medical supplies, including trauma medicine and portable trauma bags for first responders.

As Israeli airstrikes continued pounding Gaza, around 30 Arab and Western leaders attending a summit on Saturday in Cairo, Egypt, called for establishing a mechanism to guarantee the progress of peace talks and finding a just solution to end the Israel-Palestine conflict.

Egypt and Jordan harshly criticized Israel over its actions in Gaza at the Cairo Summit for Peace, which was initiated by Egyptian President Abdel Fattah al-Sisi, a sign that the two Western allies that made peace with Israel decades ago are losing patience with its war against Hamas.

United Nations Secretary-General Antonio Guterres urged sustained humanitarian aid to be delivered to Gaza. He said the grievances of the Palestinian people are legitimate and long, but nothing can justify the reprehensible attacks by Hamas that terrorized Israeli civilians. But the Hamas attacks "can never justify the collective punishment of the Palestinian people", he added.

Zhai Jun, China's special envoy on the Middle East issue, advocated the "two-state solution" at the summit and reiterated that China opposes and condemns all actions that harm civilians and violate international law.

Arab League Secretary-General Ahmed Aboul Gheit said the international community should agree to a comprehensive political settlement that guarantees Palestinian people their independent state.

The conflict has claimed more than 5,800 lives and wounded over 20,000 as of Saturday, according to the UN. The military wing of Hamas said in a statement on Friday that it had released two hostages, both United States citizens.

At a separate summit on Friday, leaders of the Association of Southeast Asian Nations and the Gulf Cooperation Council condemned all attacks against civilians and called for "a durable cease-fire" as the Middle East conflict intensified. They also called for the "most effective and efficient" access for humanitarian aid and the restoration of electricity and water services.

Prime Sarmiento in Hong Kong contributed to this story.