At least seven people were killed and a further 22 injured in an Israeli air attack on Khan Younis in the southern Gaza Strip, a staff member of the European Hospital in the city reported on Monday.
A spokesman for the Israel Defense Forces (IDF) said the report was being investigated. Reports from residents of the city said that those killed had been escorting humanitarian aid on the orders of the Palestinian militant movement Hamas.
There have been increased reports of looting of aid by civilians in the Gaza Strip, amid warnings from aid organizations that public order is breaking down.
US Secretary of State Antony Blinken met with Israeli Defence Minister Yoav Gallant on Monday, the US State Department said.
"The Secretary emphasized the need to take additional steps to protect humanitarian workers in Gaza and deliver assistance throughout Gaza in full coordination with the United Nations," US spokesman Matthew Miller said.
Blinken also updated Gallant on "ongoing diplomatic efforts to advance security, governance, and reconstruction in Gaza during a post-conflict period and emphasized the importance of that work to Israel's security," Miller said.
Efforts to achieve a ceasefire in Gaza "that secures the release of all hostages and alleviates the suffering of the Palestinian people" were also discussed, Miller said.
The pair also spoke of the importance of avoiding further escalation of the conflict and of reaching a diplomatic resolution that allowed both Israeli and Lebanese families to return to their homes.
"Secretary Blinken reaffirmed the United States' ironclad commitment to Israel’s security," Miller added.
Meanwhile, an air raid siren rang out over the Israeli coastal city of Ashkelon for the first time in several weeks.
According to paramedics, two people were injured as they ran into shelters in the city, about 10 kilometres along the coast northwards from the Gaza Strip.
Warning sirens also sounded in towns on the edge of the Gaza Strip, according to the military.
The Palestinian militant group Islamic Jihad claimed responsibility for the attacks.
The Israeli military said that two missiles fired from the northern Gaza Strip had been intercepted by Israel's missile defence system.
Previously, the defence system intercepted a projectile fired from Rafah in the south of the territory.
Israel's military has been deployed in Gaza with the declared aim of destroying Hamas, which was in control of the densely populated coastal territory before war broke out on October 7. The war was triggered by an unprecedented massacre by Hamas gunmen in Israeli communities near the Gaza border.
According to the Israeli military, a total of around 20,000 rockets, mortar shells and drones have been used against Israel on various fronts since the start of the war. The fronts include: the Gaza Strip, Lebanon, Syria, Iran, Iraq and Yemen.