Gaza's civil defence agency said 22 people, including at least six children, were killed in Israeli strikes in the Palestinian territory.
Agency spokesman Mahmud Bassal said one strike killed ten members of the same family sheltering in the Al-Mawasi area west of Khan Yunis, while another on the Al-Shati camp near Gaza city left ten dead and more than 30 wounded.
The victims in Al-Shati were from two families, he added.
Asked for comment, the Israeli military said it was "looking into the reports".
"The explosion was massive, like an earthquake," said Zuhair Judeh, 40, who saw the Al-Shati air strike.
"The bodies and remains of the martyrs were scattered."
"You can't predict when or why they'll bomb you," 36-year-old Abeer al-Sharbasi said after the Al-Shati strike.
"We have nothing left but to surrender ourselves to God."
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The bombings came as Israeli Prime Minister Benjamin Netanyahu met US President Donald Trump in Washington and discussed the ongoing campaign to defeat Hamas in Gaza.
Afterwards, he restated Israel's aims to secure the release of all hostages taken during the Palestinian militants' 7 October 2023 attack, and "the elimination" of its "military and governing capabilities".
Israeli attacks take toll on health system
Sobbing crowds of mourners gathered at Gaza city's Al-Shifa Hospital.
The director of the medical complex, Mohammad Abu Salmiya, told journalists that it would "be completely out of service due to the fuel shortage" within hours.
Israel's offensive and restrictions on supplies entering Gaza have taken a heavy toll on its medical system.
AFP footage from Al-Mawasi showed makeshift tents torn to shreds by the strike there, with a child's stuffed toy lying among the wreckage.
"We are extremely tired. Every day they say there is a ceasefire, but there are massacres," said displaced Palestinian Umm Ahmed.
In Khan Yunis, mourners gave a final embrace to loved ones whose bodies were laid out on the floor.
Mr Bassal later reported two other people killed in separate strikes in central Gaza and in Gaza city.
Hospitals 'directly impacted by hostilities'
Hisham Mhanna of the International Committee of the Red Cross, said the ICRC field hospital in Rafah has been the only "fully functional" hospital across the "entire area of Rafah" for more than one year "and has been under severe strain because of large mass casualty situations...".
He said the hospital has treated more than 2,200 casualties since the end of May.
More than 200 of these were pronounced dead upon arrival at the hospital during the period, he said.
Describing the scale of the challenge on RTÉ's News at One, Mr Mhanna said: "The total number of the mass casualties incidents they had to deal with exceed the entire mass casualty situations that the hospital dealt with before the beginning of the war at these [aid] distribution sites all combined."
Mr Mhanna said those presenting at the hospital are desperate and helpless, leading them to take "serious descisions and take risky routes in order to secure the bare minimum of the essential needs for their families, starting with food, some flour, canned food, anything they can find."
He said since the outbreak of the war and especially since the last ceasefire and the resumption on the 18 March of hostilities, "the entire healthcare sector in Gaza has been decimated."
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He said ongoing restrictions on urgent humanitarian aid - including medical supplies, equipment, fuel and food - have put the "remains of this healthcare system into further deeper catastrophe and under more pressure."
Mr Mhanna said many hospitals have been "directly impacted by hostilities and many doctors, nurses, healthcare staff, and patients have lost their lives while being treated or working."
"This is utterly unacceptable by us [ICRC]," he said.
"So the entire situation is chaotic, extremely perilous...and everyone in Gaza is waiting for a declaration of an [ceasefire] agreement.." and the ICRC remains more than ready to start facilitating the implementation of this agreement once it's realised and agreed by the parties," he added.
Hamas's 7 October, 2023 attack on Israel resulted in the deaths of 1,219 people, mostly civilians, according to an AFP tally based on Israeli official figures.
Of 251 hostages seized during the attack, 49 are still held in Gaza, including 27 the Israeli military says are dead.
Israel's retaliatory campaign has killed at least 57,680 people in Gaza, also mostly civilians, according to the territory's health ministry.
The UN considers the figures reliable.
The medical charity Doctors Without Borders (MSF) said a recent mortality survey conducted among its staff and their families in Gaza corroborated figures provided by the territory's health ministry.
It said the mortality rate had increased tenfold for children under five compared to estimates before October 7, 2023.
