Israeli forces have besieged two more hospitals in Gaza, pinning down medical teams under heavy gunfire, according to the Palestinian Red Crescent.

“All of our teams are in extreme danger at the moment and are completely immobilised,” the humanitarian organisation told Reuters on Sunday, adding one of its staff was killed when Israeli tanks pushed back suddenly into areas around al-Amal and Nasser hospitals in the southern city of Khan Younis.

Palestinians who fled the raid described days of heavy fighting, mass arrests and forced marches past dead bodies in interviews with the Associated Press on Sunday.

“From time to time, the tank would fire a shell,” Kareem Ayman Hathat, who lived in a five-storey building about 100 metres from the hospital, told AP. “It was to terrorise us.”

The head of Israel’s southern command, Maj Gen Yaron Finkelman, called the Shifa raid a “daring, tricky and most impressive operation”, saying it would end “when the last terrorist is in our hands, alive or dead”.

Israel claims that the hospitals are used to harbour fighters while Hamas denies using the facilities for military ends and accuses Israel of war crimes.

On Saturday, Hamas-run media alleged that 19 Palestinians had been killed in Gaza City and several others wounded at a humanitarian aid distribution point, a claim Israel has denied. According to Hamas, the killings occurred while the victims were waiting for aid trucks at the Kuwait roundabout, where they were reportedly struck by tank fire and shells from the Israeli occupation army.

Footage from AFPTV showed wounded people arriving at al-Ahli hospital, some being transported by donkey cart. “There were very serious injuries, some of whom were injured by shrapnel. The reality is tragic, difficult and challenging,” Mahmud Basal, spokesperson for the civil defence department in Gaza, told AFP.

The Israeli army has denied carrying out an attack on the crowd. In a statement, the IDF dismissed the reports as inaccurate, asserting that there was no aerial strike or gunfire from Israeli forces directed at the aid convoy. “Preliminary findings have determined that there was no aerial strike against the convoy, nor were there incidents found of [Israel] forces firing at the people at the aid convoy,” it said.

On 29 February, at least 112 people were killed and 280 injured at the Nabulsi roundabout, along the coastal road on the south-west edge of Gaza City, when desperate crowds gathered around aid trucks in the hope that food would be distributed and Israeli troops opened fire.

At the time, Israeli military officials told the Guardian and other news outlets their forces had only opened fire on a crowd that threatened them after the aid convoy had moved on, and that most of the casualties were caused earlier by the stampede or people being knocked down.

Both sides are grappling with indirect talks in Doha as they strive to secure a hostage release agreement and a temporary ceasefire in Gaza.

A senior official from Hamas told AFP there were still significant gaps in the negotiations, citing how the stark differences were fuelled by “what they perceive as Israel’s misinterpretation of their flexibility as a sign of weakness”. According to the official, Israel is pushing for a temporary ceasefire that would allow for future aggression against the Palestinian people rather than a comprehensive agreement.

As stated in a report by the Qatar-headquartered Al Jazeera on Saturday, a key discrepancy centres on the number of Palestinian security prisoners Hamas is insisting must be liberated to guarantee the return of female IDF soldiers detained in Gaza since the 7 October attack.

The US intelligence chief, Bill Burns, and his Israeli counterpart, David Barnea, left Qatar late on Saturday after the talks, a source briefed on the talks told AFP. “The talks focused on details and a ratio for the exchange of hostages and prisoners,” the source added, explaining that “technical teams remain in Doha”.

The war was triggered in October when Hamas killed 1,200 people, mostly civilians, in its surprise attack in southern Israel. The militant Islamist organisation also abducted about 250 people.

The military offensive launched by Israel in the aftermath of the October attack has so far killed more than 32,000 people in Gaza, mostly women and children, according to local health authorities. A relentless bombardment has reduced swaths of the territory to rubble, displacing more than 80% of the population.

António Guterres, the UN secretary general, who visited Egypt’s border with Gaza on Saturday, said it was time to “truly flood Gaza with lifesaving aid” and called the starvation inside the territory a “moral outrage”.

There has been sharp and widespread criticism of Israel, which is accused of obstructing aid with cumbersome bureaucracy, arbitrary denials of permission and a refusal to open major access points to Gaza that would allow rapid flows of assistance.

Hamas on Saturday released a video on the death of an Israeli hostage, who allegedly died due to a lack of food and medicine. “Although he survived the Israeli defence forces’ attacks, he did not escape the lack of food and medicine,” reads the caption. “What the people of Gaza are suffering from the siege and the shortage of food and medicine, your prisoners will also suffer.”

Israel denies the charges of obstructing aid, with spokespeople saying there are no limits on the entry of food, water, medicine or shelter equipment into Gaza.

Meanwhile, the head of the UN Palestinian refugee agency (Unrwa) said on Sunday that Israel had informed theUN that it would no longer approve Unrwa food convoys to north of Gaza.

“This is outrageous and makes it intentional to obstruct lifesaving assistance during a man-made famine. These restrictions must be lifted,” the Unrwa head, Philippe Lazzarini, said on the social media platform X.

The agency has been at the centre of a bitter controversy after being accused by Israel of collaborating with Hamas in Gaza. It denies the charge and says no solid evidence has been presented to support the allegation.

Unrwa staff have been subjected to a systematic campaign of obstruction and harassment by the Israeli military and authorities since the beginning of the conflict in Gaza five months ago, according to internal UN documents obtained by the Guardian and revealed last week.