Trucks carrying aid arrived into southern Gaza on Saturday, the first convoy of humanitarian supplies since Israel began a devastating siege 12 days ago and after further heavy Israeli bombardment overnight that killed dozens of Palestinians.

U.S. President Joe Biden had said this week that agreement had been reached for 20 aid trucks to cross through Gaza's Rafah border point with Egypt, and added on Friday he believed those first trucks would pass through within 48 hours.

Witnesses said aid trucks exited the crossing after checks and proceeded into Gaza's southern area including the major towns of Rafah and Khan Younis where hundreds of thousands of people displaced by Israel's unrelenting air war are sheltering.

However, Palestinian officials were disappointed that fuel supplies were not included and added that the relief was only three percent of what used to get into Gaza in terms of medical and humanitarian aid before the crisis.

"Excluding the fuel from the humanitarian aid means the lives of patients and injured will remain at risk. Gaza hospitals are running out of the basic requirements to pursue medical interventions," the Gaza health ministry said.

Israel's "total siege" of Gaza after the Oct. 7 cross-border attack on southern Israel by militants of the Islamist movement Hamas has left Gaza's its 2.3 million people running out of food, water, medicines and fuel.